Abstract:To investigate the relationship between the polymorphism of the nlrc3 gene in grass carp （Ctenopharyngodon idella） and resistance to Ichthyophthirius multifiliis， susceptible and resistant groups were selected from grass carp populations infected with I. multifiliis. The single nucleotide polymorphism （SNP） sites of the nlrc3 gene in the two groups were analyzed and compared. High-resolution melting （HRM） and Sanger sequencing techniques were used to validate the genotypes of the SNP sites， and the obtained SNP sites were analyzed for their association with the disease resistance traits in grass carp. The results showed that four SNPs sites were identified from the nlrc3 gene in grass carp， and three SNP sites （SNP1， SNP3， and SNP4） were successfully genotyped. Among them， SNP1 and SNP3 exhibited two genotypes each （AA and AG for SNP1， AA and GG for SNP3） and were significantly associated with resistance to I. multifiliis. The analysis of haplotype combinations and their correlation with disease resistance revealed that the genotype composed of SNP1 AG and SNP3 AA （D1） showed 100% disease resistance， while the genotype composed of SNP1 AG and SNP3 GG （D2） showed 95% disease resistance， both representing advantageous genotypes for disease resistance. The study demonstrated the existence of nlrc3 gene polymorphism in the entire population of I. multifiliis resistant grass carp， and different genotypes were significantly correlated with the ability to resist I. multifiliis infection. Among them， the D1 genotype with SNP1 AG and SNP3 AA combination exhibited the strongest resistance. These findings provide important theoretical and technical support for further breeding and prevention of I. multifiliis disease in grass carp.

Abstract:In order to study the effect of RseB gene deletion on the ability of Vibrio alginolyticus to infect the Lateolabrax maculatus， the LD₅₀， colonization ability and immune response of the L. maculatus after infection were evaluated. The results showed that the LD₅₀ of V. alginolyticus was 2.013×10⁵ cfu/mL， and the LD₅₀ of V. alginolyticus with RseB-deletion was 5.526×10⁵ cfu/mL， and the virulence of RseB-deletion V. alginolyticus decreased by 63.6%. V. alginolyticus mainly colonized in the gill， intestine and skin of L. maculatus. Compared with V. alginolyticus， the degree of intestinal vacuolization and the damage of gill tissue were lower in L. maculatus after challenged with the RseB-deletion V. alginolyticus. Transcriptome sequencing was performed on the head kidney tissues of L. maculatus challenged by wild-type and RseB-deletion V. alginolyticus， respectively. A total of 236 immune-related differentially expressed genes were found， including 122 significantly up-regulated immune genes and 114 significantly down-regulated immune genes. Most of these genes were significantly enriched in specific immune pathways such as Th1 and Th2 cell differentiation， B cell receptor signaling pathway， T cell receptor signaling pathway， and some genes were significantly enriched in apoptosis-related pathways and inflammation-related NF-kappa B signaling pathway. In summary， the results show that RseB-deletion V. alginolyticus can cause immune response of host cells and reduce virulence.

Abstract:Cyprinid herpesvirus 3 （CyHV3）， also known as Koi herpesvirus （KHV）， is a highly contagious pathogen that threatens the sustainability of cyprinid aquaculture. The ORF134 gene of CyHV3 encodes an interleukin （IL） 10 like protein. In this study， we constructed a prokaryotic expression plasmid of ORF134 and transformed it into the E. coli Rosetta （DE3） cells for expression of recombinant protein. The recombinant CyHV3-IL10 protein was purified by size exclusion chromatography and used for immunization of mice to generate monoclonal antibodies. The antibodies were then characterized by ELISA， Western blotting and immunofluorescent assay. SDS-PAGE analysis showed that the recombinant CyHV3-IL10 protein was approximately 18 ku in size and was expressed mainly in the form of inclusion bodies. The inclusion bodies were denatured， refolded and subjected to size exclusion chromatography. The recombinant CyHV3-IL10 protein was of high purity. Western blotting and immunofluorescence analyses revealed that the CyHV3-IL10 monoclonal antibodies recognized the recombinant CyHV3-IL10 protein expressed in the E. coli and HEK293 cells and could specifically detect the HEK293 cells expressing the CyHV3-IL10 protein. In summary， the availability of CyHV3-IL10 monoclonal antibodies lays the foundation for the functional study of CyHV3-IL10 and the establishment of CyHV3 diagnostic tools， and provides novel strategies for the prevention and control of the diseases caused by CyHV3.

Abstract:The omd gene encodes osteomodulin， which regulates mineralization in human bone. However， the effect of omd gene on bone mineralization in fish is still unclear. To explore the effect of omd gene on fish skeleton， we investigated the expression of omd gene in different developmental stages and different tissues of zebrafish. Using CRISPR/Cas9 gene editing technology， we constructed omd gene knockout zebrafish （omd^-/-）. The results showed that the expression of omd gene gradually increased with development in zebrafish， and the expression was higher in vertebral column and muscle. Compared with the wild-type zebrafish，no significant changes were found in bone morphology and tail muscle structure of omd^-/-zebrafish， and the calcium content of the vertebral column was down-regulated by 59.81%. Compared with the wild type， the average swimming distance and swimming speed of omd^-/- zebrafish decreased by 33.93% and 39.44%， respectively， while the relative stationary time increased by 88.26%， and the swimming ability decreased. These results suggest that the deletion of omd gene affects mineralization of the vertebral column of zebrafish and affects the mobility of zebrafish to a certain extent.

Abstract:The parental sizes of Chinese mitten crab （Eriocheir sinensis） and the growth performance of its offspring have become interestingly main topics in aquaculture industry in recent years. In this study， we applied individual growth comparison and metabolomics techniques to investigate molting and growth characteristics， intestinal microbes and hepatopancreas metabolites compositions in offspring （Size A， Size B and Size C）of the three parental standards of Chinese mitten crab （200-250 g for females and 300-350 g for males； 250-300 g for females and 350-400 g for males； > 300 g for females and > 400 g for males）. The results showed that the growth performance in the offspring of size C was better than the other two sizes in the two individual molting and growth measurements， but there were no significant differences in the molting weight gain rate， molting interval， fatness， hepatopancreas index and muscle index among the three parental sizes of offspring. The results of intestinal microbes analysis showed that α diversity index of the size A was lower than the other two sizes， but there was no significant differences among them， while the PCoA analysis showed significant differences of intestinal microbes composition among the three sizes at the genus level. Metabolomics analysis of hepatopanacas found a total of 100 different metabolites between the sizes A and B， 77 different metabolites between the sizes B and C， and 79 different metabolites between the sizes A and C. Pearson correlation analysis between different intestinal microbes and metabolites revealed that the metabolite Biopterin was significantly positively correlated with Genus Paraclostridium in the size A； the the metabolite N-acetyl-d-mannosamine was significantly negatively correlated with Phylum Nitrospira and Genus Nitrospira in the size B； the metabolite tetrahydrodipyridinate carboxylate was negatively correlated with Genus Lactobacillus in the size C. The current results of this study indicated some differences have been detected in molting and growth， intestinal microbes and hepatopancreas metabolites composition among the offspring of different parental sizes in Chinese mitten crab.

Abstract:A 180-day rice-crab co-culture experimental trial （female crab:male crab=1:1） was conducted in the saline-alkaline area of the Yellow River Estuary to find the suitable stocking density of Chinese mitten crab （Eriocheir sinensis）. The effects of different stocking densities （1.50 ind./m²， 0.75 ind./m² and 0.38 ind./m²， indicated as D150， D075 and D038 groups， respectively） on the growth and culture performance， edible tissue indices， proximate composition， physiological metabolism， contribution of food and economic performance of rice-crab were studied. The results showed that： （1） The weight gain rate （WGR）， specific growth rate （SGR） and survival rate （SR） of crab increased significantly with the decrease of stocking density， while the yield and feed conversion rate （FCR） decreased significantly. （2） There was no significant difference in edible tissue index and total edible rate among different stocking density groups， but the gonadosomatic index （GSI）， hepatosomatic index （HSI） and total edible yield （TEY） of female crab increased slightly with the decrease of stocking density. （3） With the decrease of stocking density， the contents of crude protein in muscle of females and males decreased significantly， while the contents of crude lipid in hepatopancreas of females increased significantly. （4） In terms of physiological metabolism indices， the activities of alkaline phosphatase （ALP） and acid phosphatase （ACP） in hepatopancreas of females increased significantly with the decrease of stocking density， while total antioxidant capacity （T-AOC） and the contents of malondialdehyde （MDA） in serum decreased significantly. Similarly， ALP activity in hepatopancreas of males was the highest in D038 group， while the contents of MDA in hepatopancreas and T-AOC in serum were decreased significantly and minimum value was found in D038 group. （5） The first food source of crabs under different stocking densities was formulated feed （39.39%-52.33%）. With the decrease of stocking density， the contribution of feed in food sources was increased， while the contribution of background crabs was decreased. （6） There was no significant difference in partial return and partial gross and the highest profit of each group， whilst the return-on-investment （ROI） of D038 group was significantly higher than that of other density groups. In summary， although the crabs in high-density group had the highest total yield and partial return， the crabs in low stocking density group achieved the best growth performance， health status， profit and ROI. Therefore， under the condition of this experiment， the suitable stocking density of crabs is 0.38 ind./m² under rice-crab co-culture system in the saline-alkaline area of the Yellow River Estuary.

Abstract:To investigate the relationship between morphological characters and body mass of adult Chinese mitten crabs Eriocheir sinensis， 19 morphological characters were measured and compared among E. sinensis with different body weights by quantitative and multivariate analysis， and the hepatopancreas index （HSI）， gonadosomatic index （GSI）， meat yield （MY） and total edible yield （TEY） of these crabs were compared either. The results showed that： （1） There were 13 and 11 significantly different characteristics detected in male and female E. sinensis respectively， and the values of morphological characteristics related to the length of carapace significantly increased with E. sinensis body weights increasing， but the values related to carapace width and feet length significantly decreased with E. sinensis size body weights increasing. （2） The results of principal component analysis （PCA） revealed that the polts represents different-sized individuals were relatively separated with only a slight overlap between group， indicating a quite different morphology of the individuals with different sizes. （3） Significant difference were detecte in tissue indices among different-sized crabs， and the larger crabs （Male≥300 g； Female≥150 g） had significantly lower values of GSI but significantly higher values of HSI， MY and TEY than the smaller ones. All in all， different-sized E. sinensis had significant differences in morphological characteristics and tissue indices， and they showed a significant negative correlation with GSI， which would provide a valuable reference for commercial and broodstock crabs selection.

Abstract:Proline is an important organic regulatory substance in organisms， which plays an important role in adapting marine shellfish to salinity changes. To study the effect of proline on the salt tolerance of S. constricta， high salt stress and exogenous proline were added to S. constricta. The proline content， soluble protein content and proline transporter gene expression levels of S. constricta were compared in different conditions. Under high salt stress， three free amino acids increased significantly， with the highest proline accumulation and high synthesis. Soluble protein content decreased significantly and ammonia excretion rate increased. The expressions of proline transporter SLC6A7-1 and SLC6A7-2 were significantly increased. When exogenous proline was added， the accumulation of proline content increased and reached the peak at 72 h. Soluble protein content was significantly increased， and ammonia excretion level was significantly decreased. The expression of proline transporter SLC6A7-1 increased firstly and then decreased， while SLC6A7-2 remained in a high expression state and reached its peak at 24 h. The results showed that proline could promote the synthesis of macromolecular protein and provide more energy for the salt-sensitive survival of S. constricta. It provides an important theoretical basis for further study on the regulation of proline in the salt-sensitive survival of marine molluscs.

Abstract:In this paper， Spirulina powder， Yeast， Yeast + β-Carotene were used as feed to explore the effects of feed on the growth and carotenoids accumulation of Artemia at different temperatures （20℃， 25℃， 30℃） and salinities （10， 30， 50， 70， 90）. The results showed that the survival rate and body length of Artemia fed with spirulina powder were better than those of other feed at the same temperature and salinity. On the 10th day， at 25℃， Artemia fed with spirulina powder and yeast had maximum average body length at salinity 30 （7.52 mm， 5.88 mm） （P<0.05）， while Artemia fed with yeast + β-carotene had the largest average body length （4.0 mm） at salinity 10 （P<0.05）. The average body length of Artemia in the 30℃ group was significantly longer than that in the other temperature groups at salinity 50 （P<0.05）. On the 15th day， at 25℃， Artemia fed spirulina powder had the highest survival rate （93.7%） at salinity 30. At salinity 50， the survival rate of Artemia fed with spirulina powder in the 20℃ group （94.0%） and 25℃ group （92.0%） was significantly higher than that in the 30℃ group （P<0.05）. The egg-holding rate of Artemia in each group fed with spirulina powder was significantly higher than that of other feed （P<0.05）， and gradually increased with the increases of salinity or temperature. After 15 days， the detection of carotenoids of Artemia showed that only echinenone and canthaxanthin were detected in each feed group， and β-carotene， β-cryptoxanthin， zeaxanthin and astaxanthin were not detected. The total carotenoid content of Artemia fed with spirulina powder was significantly higher than that of other groups （P<0.05）， and decreased with the increase of salinity， and the salinity 10 group was the highest （46.25 μg/g）. With the increase of temperature， it first increased and then decreased， and 25 ℃ group was the highest （46.28 μg/g）. In conclusion， Artemia fed with Spirulina powder grew best， Artemia could convert β-carotene to echinenone and canthaxanthin， with the increase of temperature， the survival rate of Artemia decreases， which accelerates Artemia growth， sexual maturity and carotenoid metabolism. If the salinity is too high or too low， the survival rate and growth rate of Artemia will be reduced， but high salt can promote sexual maturity and deplete carotenoids in Artemia.

Abstract:To have a comprehensive understanding towards the current status of ecosystem of five backbone artificial rivers of the Huangpu River in Shanghai， the fish biological integrity index （F-IBI） evaluation method was adopted to evaluate the health of water ecosystem of the artificial rivers. Professional fishing boats were rented to collect the sample fishes at 20 sections of the five rivers in June （summer） and November （autumn） of 2021， and 10 092 fish specimens were obtained， belonging to 8 orders， 17 families， 45 genera and 60 species. Taking the upper stream of the Huangpu River as the reference point， 29 primary indicators in five categories were initially set. In accordance with distribution range screening， judgement screening capability and correlation test， the F-IBI evaluation system composed of 8 indicators was constructed. The results show that Jinhui Port and Longquan Port are in state of “Good” or “Average”； there are significance spatial differences in Dazhi River， Chuanyang River and Dianpu River， ranging from “Poor” to “Good”. In summer， there were 14 sampling points in status of “Average”， and 3 sampling points were in status of “Good” or “Poor” respectively； in autumn， there were 11 sampling points in status of “Average”， 5 sampling points were in state status of “Good” and 4 sampling sites were in status “Poor”. The health of the downstream of the five artificial rivers is basically better than that of the upstream， but generally it is more uniform than that of Suzhou River， the natural tributary of the Huangpu River flowing through the central urban area of Shanghai. These results provided the reference for the environmental management of the five backbone artificial rivers of the Huangpu River in Shanghai.

Abstract:In order to understand the fish community structure in Qingcaosha Reservoir in the Yangtze River estuary， the fish resources investigation and community structure analysis were carried out in 2021. A total of 3209 individuals were collected， identified and classified into 9 orders， 13 families ，36 genera and 46 species. The freshwater carnivorous fish species are the largest. The Index of Relative Importance，IRI of Hypophthalmichthys molitrix， Aristichthys nobilis， Hemibarbus maculatus， Carassius auratus， Coilia nasus， Culter alburnus， Saurogobio dumerili and Lateolabrax japonicus were more than 1 000 and all were dominant species.The niche analysis of dominant species showed that carnivorous and omnivorous fish had higher niche overlap in food resources and living environments. The population expansions of the two groups of fish should be more limited by food， space and other resources than the low niche overlap groups. The niche overlap among Silver carp， Bighead carp and other fish is lower， and the competitions for food， space and other living resources in the reservoir are also lower. In 2021， the Margalef species richness index（D） was 5.70， the Shannon-Wiener diversity index（H'） was 3.01， the Pielou evenness index（J） was 0.78， and the Simpson dominance index（C） was 0.81. Compared with the results of fish diversity and the community structure from 2015 to 2019 in the Reservoir ， the diversity index is increasing significantly. The ABC curve analysis showed that the community structure was less disturbed by external factors.

Abstract:Goldfish， is an ornamental fish originated in China， which was domesticated from wild crucian carp. There are great differences between different types of goldfish， such as presence or absence of dorsal fin， telescope or bubble eyes， oranda and other characters. Long-term hybridization and artificial selection have produced a large number of goldfish strains， but it also leads to the confusion and complexity in determining pedigree relationship of goldfish， which makes it more difficult to distinguish goldfish strains. People tried many ways to clarify the pedigree history and hybridization relationship between various goldfish strains， but so far no progress has been made. That is why the selection history of most goldfish strains has not been clarified and the hybridization relationships of many goldfish strain have not been confirmed. In this study， tissue samples of 59 individuals from 11 Chinese goldfish strains were collected. Cross-species target gene enrichment and high-throughput sequencing were used to obtain the target gene sequencing data of each goldfish individual. Using 4 434 single-copy gene loci of zebrafish as reference sequences， the corresponding goldfish genes were grouped according to its heterotetraploid subgenome， and the enriched sequences were compared and categorized according to two subgenomes respectively. A total of 35 298 single nucleotide polymorphism （SNPs） loci were called， which were used to study the pedigree history and hybridization relationship of the goldfish strains. Principal component analyses， genetic structure analyses and phylogenetic network map of the two subgenomes were reconstructed to reveal genetic relationship of these Chinese goldfish strains and explain their selection and hybridization history： （1） The telescope and Ryukin were directly evolved from the wakin， while pearlscale and lionhead were not directly evolved from the wakin. （2） Ranchu evolved earlier than egg bubble eye， while the bubble eye had secondly lost its dorsal fin. （3） The telescope-oranda is closely related to the lionhead， which first generated the character of oranda， and later obtained the telescope eyes. （4） Pearlscale， pearlscale-oranda and telescope-pearlscale-oranda are genetically similar. Pearlscale-oranda directly evolved from pearlscale， telescope-pearlscale-oranda is the latest bred form， probably a hybrid of telescope and pearlscale-oranda. The results of this study may help to understand the evolution history of Chinese goldfish and provide some reference for the classification and breeding of goldfish varieties.

Abstract:In order to ascertain the fish community structure in the southern waters of the Yangtze River Estuary， 12 stations were set up in the North Port， the North Channel and the South Channel of the Yangtze River Estuary in April （spring） and September （autumn） of 2020， and two voyages of fishery resource surveys were conducted using single bag trawls （minimum mesh size 25 mm）. By calculating individual， weight resource density， relative importance index， α-diversity index， combined with multiple factor regression analysis and canonical correspondence analysis （CCA）， we could determine the spatio-temporal change rule of the community and the impact of environmental factors on the distribution. In this study， 49 species of fish were collected， belonging to 16 orders， 25 families and 41 genera. All of them are warm temperature and warm water fish. The majority of them are estuarine fish， while the narrow salt fish are less and distributed regionally. The resource density in spring is higher than that in autumn， while the weight resource density in autumn is higher than that in spring. Coilia mystus， Coilia nasus， Collichthys lucidus and Miichthys miiuy were dominant species in both seasons. In spring， Miichthys miiuy's individual resource density has the highest contribution rate to the total density and the most significant impact. In autumn， the contribution rate of the individual resource density of Harpadon nehereus is the highest， but the influence of the individual resource density of Coilia nasus is the most significant. The results of individual and weight diversity index showed that H'， J' and D' in autumn were higher than those in spring， while the average value of C' in spring was higher. The surface salt temperature of the water surface in the study area is affected by many dynamic factors and there is a large seasonal change. The resource density plane distribution map and the ranking map reveal that certain groups have a life habit of tending to temperature and salt.

Abstract:This research aims to study the source， spatial distribution characteristics and ecological risks of diuron in the coastal waters of the Yangtze River Estuary and Shanghai， water samples from 24 stations in the coastal waters of the Yangtze River Estuary， Hengsha Island （inland） waters and the waters near the Yangtze River Estuary Chinese sturgeon reserve were collected from October to November 2021， and the content of diuron in the surface water samples of each station was analyzed by solid phase extraction and high performance liquid chromatography tandem mass spectrometry. According to the test results， the mass concentration of diuron was detected in the water samples of 24 stations in three different regions. Among them， the detection range of diuron mass concentration at 10 stations along the Yangtze River Estuary in Shanghai was 182.43-439.38 ng/L， and the detection rate was 100%. The detection range of diuron mass concentration at 9 stations in Hengsha Island （inland） water area is 83.48-369.25 ng/L， and the detection rate is 100%. The detection range of diuron mass concentration at 5 stations near the Chinese sturgeon reserve is 1.97-2.85 ng/L， and the detection rate is 100%. The spatial distribution of diuron is mainly affected by factors like water transport， ship maintenance， agricultural activities， tides and seawater dynamics. Besides， the ecological risk assessment shows that the coastal waters along the Yangtze River Estuary in Shanghai are potentially at medium risk. Farming areas in Hengsha inland waters are at medium risk， and the nearby waters of the Nature Reserve are at low risk. The results show that the environment in the coastal waters of the Yangtze River Estuary in Shanghai is being threatened by the diuron， especially in the major ports and docks along the Yangtze River Estuary in Shanghai as well as the agricultural areas and river intersections in the Hengsha Island area. Although it will not threaten the Chinese sturgeon reserve in the short run， it still deserves attention.

Abstract:China is continuously promoting the transformation of rural green economy and rural revitalization strategy， and various ecology-oriented agricultural development models such as the pastoral complexes are new ways of rural revitalization construction， driving the transformation of traditional agriculture to modern agriculture development while driving the carbon sequestration and emission reduction in agriculture. Taking the EOD （Ecology oriented development） model of the pastoral complex in Fengjing Township， Jinshan District， Shanghai as the research object， based on on-site research and data statistics， the carbon input and output in the park， as well as the flow and storage of carbon among various areas in the garden， were analyzed； meanwhile， based on the carbon source and sink inventories and at the same time， the carbon balance characteristics of each zone in the pastoral complex were analyzed based on the carbon source and sink inventories and estimation results. The results show that the carbon balance of the pastoral complex in Jinshan District， Shanghai in 2021 is a net carbon sink area， with a net carbon sink of 152.09 tC， including emissions of 588.79 tC and carbon fixation of 740.88 tC. Within the pastoral complex， the crop cultivation area is the largest net carbon sink area through low-carbon organic cultivation mode， with a net carbon sink of 185.76 tC. The aquaculture area has a net carbon sink of 62.20 tC through the efficient multi-stage water and grass recycling model； the stereoscopic agriculture area with a high spatial utilization rate is the carbon source area with a net carbon sink of -10.81 tC due to the significant carbon emission from agricultural fertilizers； the production and living area is the largest carbon source area with a net carbon sink of -85.05 tC， and human cultural and tourism activities are the largest carbon emission source. The analysis combines the carbon flow of this pastoral complex. It proposes four directions of agricultural carbon reduction and sink increase by developing high material recycling rate， high spatial utilization rate， low carbon organic planting mode， and agricultural science management.

Abstract:Anchovy（Engraulis japonicus）is an important fishing target in the Yellow Sea， and it is also the main prey for large fishes such as Japanese-Spanish mackerel.Exploring the distribution and early growth characteristics of anchovy is important for understanding of the recruitment mechanism.In this study， based on the survey data of the cross-section in the central Yellow Sea in the summer of 2019， the relationship between the distribution of eggs， larvae and juveniles and environmental factors was investigated using Tweedie GAM model. Furthermore， based on the otolith microstructure analysis， the daily age and body length composition of larvae and juveniles were estimated， and the early growth equation of power function was constructed by extrapolating the hatching date.The results showed that in the summer of 2019， a dense distribution area of anchovy eggs occurred in the line section of 35.5°N in the south of Shandong Peninsula， and the dense distribution area of larvae and juveniles occurred in the area of 35.5°N-36.5°N along 123.5°E longitudinal sections.Salinity has a significant effect on the distribution of anchovy eggs， larvae and juveniles， the optimum salinity range was 30-32，on the other hand， the water temperature only has a significant effect on the distribution of anchovy eggs， and the optimum temperature range was 23-26 ℃.Analysis of daily otolith increment for 211 larvae and juveniles showed that the range of body length was 4-24 mm with the dominant length group of 12-14 mm， the age range was 12-40 days with dominant age group of 18-20 days， and the otolith growth rate ranged from 3.08 μm/d to 5.90 μm/d.The variation pattern in the daily otolith growth rate of larvae and juveniles was different between samples in July and August， which might be related to the difference in the water temperature between different months.This study provides scientific basis for the early growth and recruitment mechanism of anchovy resources.

Abstract:In order to understand the structural characteristics of nekton community near Wailingding marine ranching area， a comprehensive survey of resources and environment was carried out in the spring and autumn of 2020， and the composition of nekton， dominant species， catch rate and community structure characteristics were analyzed，and a nekton community structure data matrix was constructed to analyze the influence relationship between nekton community structure and environmental factors.A total of 73 species of nektons were collected， belonging to 12 orders and 30 families and 49 genera， the largest number of fish with 47 species， 10 species of shrimps， 9 species of crabs， 4 species of cephalopods， and 3 species of mantis shrimps.Index of relative importance （IRI） results shows that there are four dominant species with IRI＞1 000， namely Pampus argenteus， Thrissa kammalensis， Loligo beka and Leiognathus ruconius，among which Pampus argenteus and Thrissa kammalensis were the common dominant species in both seasons. The results of Margalef index （D'）， Shannon-Wiener index （H'） and Pielou index （J'）showed that spring was higher than autumn， one-way analysis of variance （ANOVA） showed that H' and J' were significantly different in different seasons， however D'was no significant seasonal difference. Similarity of percentage （SIMPER） revealed that the species with the highest contribution in spring was Thrissa kammalensis， and the highest contribution in autumn was Ilisha indica，the average dissimilarity was up to 78.64% and the cumulative contribution rate of anisotropy was 42.72%. Redundancy analysis （RDA） shows that chlorophyll a， water mass and petroleum are the main environmental factors that affect the community structure in Wailingding marine ranching area.The study shows that the high-density area of catch mainly appears in the coastal waters of islands and reefs，and the community composition of swimming organisms is obviously different in different seasons， which may be related to the law of life history， the fishing moratorium policy and the influence of key environmental factors in the area.The result can provide basic data and theoretical reference for scientifically and reasonably understanding the characteristics of nekton community in the construction area of marine ranching， guiding and evaluating the ecological restoration effect of marine ranching.

Abstract:In order to further understand the characteristics of the life history of the Sepia esculenta population in the coastal waters of Jiangsu， the feeding ecology and nutritional niche of the Sepia esculenta were studied by using the carbon and nitrogen stable isotope analysis method based on the samples collected in the coastal ports of Jiangsu. The results showed that there was no significant difference in δ¹³C and δ¹⁵N values between male and female populations of Sepia esculenta； There was a significant correlation between them； the nutritional niche width of male Sepia esculenta （SEAc=0.57‰²） was not significantly different from that of females （SEAc=0.63‰²）， and females were slightly larger than males， and both are highly overlapping （0.62）. Isotopic cluster analysis showed that Sepia esculenta individuals could be divided into three mantle length groups of 75-114 mm， 115-184 mm and 185-204 mm； The niche width of the 114 mm mantle length group was the smallest （SEAc=0.39‰²）； only the niche overlap rate between the 75-114 mm and 115-184 mm mantle length groups was moderate （0.34）， and the niche overlap rate among the other mantle length groups was low. According to the analysis， the change of δ¹³C value of Sepia esculenta was mainly affected by the isotope baseline value and the migration pattern of Sepia esculenta， while the change of δ¹⁵N value was mainly affected by the feeding effect of Sepia esculenta； the height of food resources and habitat utilization between female and male golden squid groups were highly similar； Sepia esculenta at different developmental stages had obvious differences in nutritional niche.

Abstract:The southwest Atlantic Ocean is one of the most important fishing areas in the world， and fishing countries there include coastal states， such as Argentina， and many non-coastal states， such as China and Japan. The four main commercial species with the highest annual average yield are Illex argentinus， Merluccius hubbsi， Sardinella brasiliensis and Micropogonias furnieri. Exploring impacts of climate variability on the fishery ecosystems is conducive to the establishment of an ecosystem-based approach to the protection and rational utilization of the fishery resources. The responses of biological factors（major commercial species）， abiotic factors （environmental conditions）， and nutritional structure （food web） of the ecosystems to climate variability were summarized based on the perspective of fishery resources and ecosystem. In conclusion， it was found that climate change can affect environment and had impacts on fishery resources and nutritional structure of the ecosystem. For providing ecosystem-based management strategies， selecting indicator species to represent ecosystem changes and investigating confounding impacts of human activities and climate changes in the future research would provide more realistic responses of southwest Atlantic ecosystems to climate variability.

Abstract:In this study， we identified the important fish pathogenic bacterium， Edwardsiella piscicida， GadBCD， the strong acid resistance system and its function. Sequence analysis and co-transcription experiments showed that the GadBCD system consists of one glutamic acid decarboxylase， one glutaminase and three transporters， which form a manipulator. qRT-PCR revealed that gadBCD expression was largely unchanged upon strong acid and high temperature stimulation of bacteria， but significantly up-regulated upon hydrogen peroxide and host serum stimulation. A GadBCD system deletion mutant strain ΔgadP was constructed using homologous recombination， and experiments comparing the growth curve and survival rate under acidic stress of wild strain and ΔgadP revealed that the GadBCD system is not only an important player in the resistance of E. piscicida to medium to strong acids， but is also required for resistance to strong acids. GadBCD was found to be involved in bacterial virulence by comparing wild strain and ΔgadP in terms of biofilm formation， motility， resistance to host serum killing， and infection of cells. In conclusion， the GadBCD system is an important strong acid resistant system of E. piscicida and is involved in bacterial pathogenesis.

Abstract:With the changes in tuna supply and demand pattern， trade policy， resource endowment and other factors in the world， the tuna trade relationship is undergoing a period of diversification. Understanding the characteristics of the global tuna trade network and the changes in China’s tuna trade pattern is important for China to optimize its tuna trade policies. In this study， the trade networks of fresh or chilled and elaborate tuna are researched using the complex network analysis method. Changes in the global tuna trade network pattern and the characteristics of China’s tuna trade network are investigated. In addition， the Hubness measures index （HMI） is employed to measure the degree of China’s reliance on its principal tuna export trading markets. Results are as follows： （1） From 2002 to 2020， the global fresh or chilled tuna trade network density increased from 0.027 to 0.030. The United States， Japan， and Spain had comparatively high betweenness centrality， whereas China’s node degree， betweenness centrality， and strength were all small. （2） The network density of elaborate tuna trade increased from 0.049 to 0.063. Thailand’s betweenness centrality ranked first in the world. China’s node degree， betweenness centrality and strength all increased significantly， but its betweenness centrality ranked relatively low. （3） With the exception of a few countries （regions）， the HMI of China’s primary tuna export markets are all low and generally declining. Thailand is China’s greatest export market for tuna， but the average proportion of Chinese-origin tuna in Thailand’s total tuna imports is only 6.9%. Conclusions are as follows： （1） The density of world tuna trade network is low with an overall rising trend. In trading network for fresh or chilled tuna， the United States， Japan and a few European countries maintain prominent positions and exert considerable influence over the industry. In the elaborate tuna trade network， Thailand is the most influential country； （2） The pattern of China’s tuna trade network has changed significantly， and its status is progressively rising； however， its overall influence does not correspond to the ranking of trade scale； （3） China still has great potential for trade collaboration with major tuna import markets.

Abstract:China plays an increasingly important role in the international distant water fishery， and the distant sea squid fishing is an important part of China's distant water fishery. Studying the international competitiveness of China's distant sea squid fishing is conducive to the sustainable development of China's distant sea fishery. Taking China's ocean squid fishing as an example， this paper uses the trade data between China and major countries in the world from 2000 to 2020， adopts the Herfindahl-Hirschman index and the CMS model， and analyzes the trade structure and related main influencing factors of our country's ocean squid fishing products. The results show that in recent years， the United States， Japan and South Korea are the main import and export countries of China's squid products， and China's trade in frozen squid products with the United States， Japan and South Korea is in a surplus state. According to the calculation results of the model， the trade of China's distant-water squid fishing is divided into three stages： 2000-2008， 2009-2018， and 2019-2020. On the whole， the export market of our country's ocean squid fishing products is stable and can adapt to the adjustment and changes of the product structure in the international market， but there are also problems in the unbalanced import market， strong dependence on external market demand and showing a downward trend， and insufficient product competitiveness. Therefore， this paper puts forward suggestions for improving the development of our country's distant-water squid fishing from three aspects： optimizing the market structure， establishing an information platform， and revitalizing resource endowments， so as to improve the international competitiveness of China's distant-water fishery.

Abstract:The high-quality development of ecological fishery is the strategic goal of China's fishery development. Studying the path of high-quality development of ecological fishery in Guizhou province for ecological restoration of the Yangtze River basin and the Guizhou section of the Pearl River basin is of great significance for consolidating and expanding the achievements of poverty alleviation， comprehensively promoting rural revitalization， building ecological civilization pilot demonstration areas and other provincial decision-making and deployment， as well as jointly building the "the Belt and Road"， carbon peak， carbon neutrality and other major national strategic tasks. Based on the survey of the current situation of ecological fishery development in Guizhou Province and the analysis of the data in the China Fishery Statistical Yearbook， this study combed the achievements， constraints and development opportunities of ecological fishery development in Guizhou Province during the 13th Five-Year Plan. Then， according to the guiding document of Guizhou Province's ecological fishery development， the Opinions of the General Office of the Provincial People's Government on Accelerating the High-quality Development of Ecological Fisheries and the characteristics of Guizhou Province's ecological fishery industry， the concept and basic principles of high-quality development of ecological fisheries in Guizhou Province are tentatively put forward. And we further put forward suggestions and countermeasures for the high-quality development of ecological fishery in Guizhou Province from six aspects： expanding the space of ecological fishery， promoting diversified ecological aquaculture models， promoting the integrated development of industries， making the recreational fishery bigger and stronger， increasing the investment in scientific and technological innovation in fishery， and improving the ecological fishery system guarantee system， in the hope of providing reference for the high-quality development of ecological fishery in Guizhou Province.

Abstract:The trade of aquatic products between China and ASEAN countries is becoming increasingly close， and ecological and environmental security is of great significance in the process of building green "Belt and Road". This paper used the DEA-Malmquist Luenberger index method to calculate and decompose the green total factor productivity index of fishery in ASEAN countries from 2001 to 2020， and established a two-way fixed-effect model to empirically analyze its influencing factors and mechanisms. The results show that the average fishery green total factor productivity index of the nine ASEAN countries shows a state of "rise-fall-rise"， and the level of fishery green total factor productivity needs to be improved. Trade volume of aquatic products， the "Belt and Road" Initiative and human capital all have a positive impact on improving the level of green total factor productivity of fishery， and there is a negative correlation between per capita GDP and green total factor productivity of fishery. Among the mechanisms， the "Belt and Road" Initiative has significantly promoted technological progress， technological efficiency and scale efficiency. It is recommended that China and ASEAN countries open up aquatic products trade markets， flexibly use trade policies， improve the quality of economic development， and formulate development plans suitable for their own countries， so as to achieve coordinated development of aquatic products trade between China and ASEAN countries.