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  • Phytoplankton community structure, functional groups and their relationship with environmental factors in Dongguan Ecological Park
    ZHAO Junhui, WANG Yang, WANG Yakun, WU Pengju, HUANG Na, CHEN Liping, LIU Qigen, HU Zhongjun
    Journal of Dalian Ocean University. 2023, 38(6): 1020-1031. https://doi.org/10.16535/j.cnki.dlhyxb.2023-084
    Abstract (1795) PDF (713) HTML (3)   Knowledge map   Save
    To investigate the structural characteristics of phytoplankton communities, functional groups and their relationship with environmental factors in Dongguan Urban Wetland Park, the phytoplankton community structure and environmental factors in the water environment were quarterly investigated at 7 sites in the Central Islands and Moon Lake of Dongguan Ecological Park from April to December 2019 by the traditional classification method, functional group classification method and comprehensive nutrient status index method. The results showed that 137 species (genera) of phytoplankton were identified in Dongguan Ecological Park, with the most species number in Chlorophyta and all the dominant species in Cyanophyta throughout the year. There were annual average phytoplankton abundance of (16.83±1.97)×107 ind./L and biomass of (23.00±3.00) mg/L, with significant differences in abundance and biomass among seasons (P<0.05), and significant differences between seasons and lake areas (P<0.05). Cluster analysis (CA) showed that there were significant changes in the composition of phytoplankton species between seasons (P<0.05). Phytoplankton in Dongguan Ecological Park was divided into 24 functional groups, with dominant functional groups D, F, H1, J, Lo, MP, P, S1, SN, W1, X1 and Y, and seasonal changes. Redundancy analysis (RDA) revealed that water temperature (WT),  ammonia nitrogen (NH+4-N), pH and total phosphorus (TP) were the main environmental factor affecting the dominant phytoplankton species and functional groups. A comprehensive analysis of the water quality evaluation by single factor evaluation method, trophic level index (TLI), functional group Q index, phytoplankton standing crop, chlorophyll-a and phytoplankton diversity indices showed that Dongguan Ecological Park was in a moderately eutrophic or polluted state, with severe organic pollution and nitrogen as the main pollutant. The phytoplankton community in Dongguan Ecological Park was shown to be dominated by Cyanophyta, and the water environment to be in a moderately eutrophic or moderately polluted state. It is necessary to strictly control external pollution and strengthen the water purification capacity of the water itself.
  • Current status and high quality culture industry development strategies of mud crab in genus Scylla in China: a review
    WANG Chunlin
    Journal of Dalian Ocean University. 2023, 38(6): 913-924. https://doi.org/10.16535/j.cnki.dlhyxb.2023-282
    Abstract (1749) PDF (837) HTML (4)   Knowledge map   Save
    There are four species of mud crab in genus Scylla, including Scylla aradamosain, S.serrata, S.tranquebarica, and S.olivacea, in which S.paramemosain as the largest mariculture crab species in China is widely distributed in the southeast coast of China. S.paramemosain is known as the “masterpiece of seawater” due to its delicious taste and high price. In recent years, however, the aquaculture area, aquaculture yield, and capture yield of Chinese mud crab have shown a downward trend. At the same time, the demand for mud crab has been continuously increasing, leading to increasingly prominent supply-demand contradictions. This article summarizes an overview of the breeding, seedling cultivation, aquaculture models, artificial feed, diseases, and other aquaculture status of Chinese mud crab, as well as the types, fishing, and processing of mud crab resources. It is suggested that China’s mud crab industry should mainly focus on expanding breeding space, breeding high-quality varieties, improving seedling cultivation level, and breaking through intermediate cultivation technologies. Efforts will be made to optimize the breeding mode and develop new models, develop artificial feed combinations, develop new forms of products, and strengthen the brand of mud crab in the future. The findings will provide scientific references for promoting high-quality development of mud crab culture industry.
  • Impact of vertical structure of water temperature during different fishing seasons on CPUE of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean using GAM and BRT models
    LIU Yue, CHEN Xinjun, WANG Jintao
    Journal of Dalian Ocean University. 2023, 38(6): 1063-1071. https://doi.org/10.16535/j.cnki.dlhyxb.2023-041
    Abstract (1746) PDF (566) HTML (1)   Knowledge map   Save
    To explore the effect of water temperature at different depths and vertical structure of water temperature on catch per unit effort (CPUE) of neon flying squid (Ommastrephes bartramii) and to provide a guidance for the improvement of neon flying squid production efficiency, the influence of 0-300 m water temperature and vertical structure at different depths on the CPUE were analyzed based on the fishery data from May to November from 2015 to 2019, combined with the marine environmental data of the same period, the generalized additive model (GAM) and the boosting regression tree (BRT) during different fishing seasons. The stability and accuracy of the two models were evaluated using repeated ten-fold cross-validation. The results showed that the key factors screened by the GAM model based on the magnitude of deviation explained were found to be latitude (Lat), 150 m layer temperature (T150), 50-100 m water temperature gradient (G50-100), longitude (Lon), and 100-150 m water temperature gradient (G100-150) during the early fishing season (May to July). The BRT model screened factors in order of contribution rate were shown to be sea surface temperature (T0), 0-50 m water temperature gradient (G0-50), 50 m layer temperature (T50), Lat, and G50-100. During the main fishing season (August to November), however, the key factors selected by the GAM model based on the magnitude of deviation explained were Lat, Lon, T0, G0-50, and G50-100. The BRT model selected factors in order of contribution rate were G0-50, Lon, T0, Lat, and T50. The comparison of the two models indicated that BRT was better than the GAM to analyse the actual fishing data, with different key factors affecting CPUE in different stages of fishing season. The great influence on CPUE was observed in the upper-middle water temperature in the early fishing season, and great contribution to CPUE was found in the shallow water temperature in the main fishing season.
  • A lightweight fish object detection method improved based on the YOLOv7 model
    MEI Haibin, HUANG Zheng, YUAN Hongchun
    Journal of Dalian Ocean University. 2023, 38(6): 1032-1043. https://doi.org/10.16535/j.cnki.dlhyxb.2023-085
    Abstract (1689) PDF (622) HTML (2)   Knowledge map   Save
    To address the reliance on manual labor for fish detection and recognition in commercial fishing vessel electronic monitoring systems, a lightweight real-time fish detection model called YOLOv7-MRN was proposed in which the backbone network of YOLOv7 was replaced with the MobileNetv3 backbone network to reduce computational complexity. Additionally, receptive field modules were incorporated to enhance the network’s feature extraction capabilities. The neck feature fusion network RFB to suppress irrelevant weights was redesign by introducing a normalization-based attention mechanism module NAM. The test of the HNY768 offshore fishing vessel electronic monitoring video fishery dataset revealed that YOLOv7-MRN achieved mAP@0.5 of 86.5%, with only 9.8% of the computational load compared to the original model. The inference speed of the model was improved by 121.69% on GPU and 219.09% on CPU. In comparison to other models, YOLOv7-MRN exhibited superior performance in practical fish detection, particularly in strong sunlight conditions. These findings indicate that the YOLOv7-MRN model proposed here can be deployed in electronic fishing vessel monitoring systems with reduced computational resource consumption to accomplish fish detection tasks.
  • Function analysis of zebrafish (Danio rerio) hoxb3a gene in early heart development
    WANG Bingqi, HE Hongyang, WANG Jie, ZU Yao?
    Journal of Dalian Ocean University. 2023, 38(6): 956-963. https://doi.org/10.16535/j.cnki.dlhyxb.2023-089
    Abstract (1679) PDF (680) HTML (1)   Knowledge map   Save
    To investigate the regulatory role of hoxb3a gene in early development of genetically modified strains of zebrafish (Danio rerio) heart, hoxb3a gene was knocked down in the zebrafish embryos using gene silencing technology (Morpholino), and the effects of hoxb3a on zebrafish heart development were analyzed by combining microscopic observation and analysis, real-time fluorescence quantitative PCR, and in situ hybridization. The results showed that the hoxb3a knockdown group (hoxb3a morphant) showed enlarged pericardial cavity, abnormal heart looping angle and altered atrial and ventricular morphology. The in situ hybridization assay determined the expression regions of hoxb3a in different spatial and temporal regions, and changes in the location of its expression indicated that hoxb3a was related to the involvement of neural crest cells in the formation of heart development. In the hoxb3a knockdown group, the expression level of some key cardiac genes was found to be changed at 3 days after fertilization compared with the control embryos, significantly increase in the expression of cardiac progenitor genes nkx2.5 and gata4, and nppa, a key gene for atrial formation. The expression level of fgf8a, a gene related to neural crest development, was shown to be significantly increased. The findings indicate that hoxb3a plays an important role in early cardiac development in zebrafish embryos and influences cardiac development by regulating the expression level of nkx2.5, gata4, nppa and fgf8a and other related transcription factors, which may provide new ideas for early cardiovascular development research.
  • Screening of SNP locus and association with growth traits of MYF5 gene in Nile tilapia (Oreochromis niloticus)
    TONG Yannan, GAO Fengying, LIU Zhigang, WANG Miao, CAO Jianmeng, YI Mengmeng, KE Xiaoli, LU Maixin, ZHU Hai
    Journal of Dalian Ocean University. 2023, 38(6): 935-946. https://doi.org/10.16535/j.cnki.dlhyxb.2023-073
    Abstract (1662) PDF (727) HTML (1)   Knowledge map   Save
    To explore the correlation between single nucleotide polymorphisms (SNP) markers of the MYF5 gene and the growth traits of Nile tilapia (Oreochromis niloticus), SNP loci were screened through PCR and sequencing, and confirmed through sequencing methods. Thirty SNP loci with high polymorphism were selected from 35 loci for genotyping analysis in the Gaoyao parent population, and association analysis between SNP loci and growth-related traits was conducted. The obtained growth related loci in Gaoyao broodstock population were verified in Gaoyao offspring population and Panyu populations. Finally, the growth traits related loci obtained above were subjected to genotyping analysis in the Hainan population for further validation. The results showed that S18 (G-1739C) was correlated with body weight and body width, S3 (A-113G) and S4 (C-170T) loci were correlated with total length, and S5 (C-323T) and S24 (C-2345T) were correlated with head length, in the Gaoyao broodstock population. In the Gaoyao offspring population, S3 and S4 loci were related to body weight; S24 was related to body length and body height. Three SNP loci related with body weight were obtained in the Panyu population, namely S7 (A-626T), S21 (C-2090G), and S32 (G-2759T), with one locus S7 related with total-length. No growth-trait related loci were found in the Hainan population. The analysis of the correlation between diplotype and growth traits in various populations showed that one diplotype significantly correlated with total length, one diplotype significantly correlated with head length, and one diplotype significantly correlated with body height was obtained in the Gaoyao broodstock population. One diplotype significantly correlated with body weight was obtained in the Gaoyao offspring population. No diploidy related to growth traits was found in the Panyu and Hainan populations.The findings suggest that S3, S4 and S18 SNP loci obtained from the MYF5 gene in this study might link or be closely related to the growth performance of Nile tilapia. These loci can be used as candidate gene markers for growth related molecular marker assisted breeding of Nile tilapia.
  • Effects of hdac8 knockout on low temperature tolerance in zebrafish (Danio rerio)
    SHI Xueling, LUO Juntao, LUO Beibei, HAN Bingshe, ZHANG Junfang
    Journal of Dalian Ocean University. 2023, 38(6): 964-971. https://doi.org/10.16535/j.cnki.dlhyxb.2023-061
    Abstract (1646) PDF (676) HTML (1)   Knowledge map   Save
    To explore the effects of knocking out histone deacetylase 8 gene (hdac8) on low-temperature tolerance of zebrafish (Danio rerio), the changes in tissue damage of gill filaments, liver, and skeletal muscles, oxidative stress-related indices, and apoptosis-related gene (caspase3, caspase9, bcl-2, bax and bcl-2/bax) expression were detected in 8 months old hdac8 deficient (hdac8-/-) and wild type (WT) zebrafish exposed to low water-temperature of 8 ℃ stress from 28 ℃ to 18 ℃ at a rate of 1 ℃/h and then to 8 ℃ at a rate of 0.5 ℃/h by histological, physiological and biochemical methods and gene expression analysis. The results showed that the median lethal time (LT50) was significantly decreased under low temperature stress in hdac8-/- zebrafish, with the LT50 of 14.5 h relative to the LT50 of 21.5 h in WT zebrafish. HE staining showed that more severe damage was observed in the gill filaments, liver and skeletal muscle in hdac8-/- zebrafish compared with WT zebrafish under low temperature stress. The ATP level in hdac8-/- zebrafish showed very significant decrease (P<0.05) at 28 ℃, without significant difference in the levels of reactive oxygen species (ROS) and malondialdehyde content between WT and hdac8-/- zebrafish (P>0.05). Under low-temperature stress, however, the hdac8-/- zebrafish had very significantly higher ROS and MDA levels than the WT zebrafish did (P<0.05), and very significantly lower ATP level than the WT zebrafish (P<0.05) did. RT-qPCR revealed that there was significantly up-regulated expression level of caspase3 in hdac8-/- zebrafish (P<0.05) at 28 ℃, without significant difference in the expression levels of other antioxidant and apoptosis-related genes (P>0.05). Under low-temperature stress, the expression levels of sod, cat, caspase3, caspase9 and bax were found to be significantly up-regulated in both WT and hdac8-/- zebrafish (P<0.05), significantly higher expression levels of these genes in hdac8-/- zebrafish than those in WT zebrafish (P<0.05). In conclusion, hdac8 knockout significantly impaired the tolerance to low temperature of zebrafish, and promoted oxidative damage and cell apoptosis at low temperature.
  • Expression and immune function characteristics of peptidoglycan recognition protein gene in disk abalone (Haliotis discus hannai)
    QIAO Kun, ZHENG Chunhua, CHEN Bei, SU Yongchang, HAO Hua, XU Min, CAI Shuilin, LIU Zhiyu
    Journal of Dalian Ocean University. 2023, 38(6): 947-955. https://doi.org/10.16535/j.cnki.dlhyxb.2023-111
    Abstract (1641) PDF (594) HTML (1)   Knowledge map   Save
    In order to investigate the immune function of the peptidoglycan recognition protein HdhPGRP-SC2-like gene in disk abalone (Haliotis discus hannai), the full-length cDNA sequence of HdhPGRP-SC2-like gene was cloned by RACE technology, and tissue distribution of HdhPGRP-SC2-like gene was analyzed in the disk abalone by real-time fluorescent quantitative PCR(qPCR). The recombinant protein rHdhPGRP-SC2-like was obtained by prokaryotic expression, and its amidase activity and immune characteristics were verified. The results showed that the cDNA of the HdhPGRP-SC2-like gene was 938 bp in length, with an open reading frame of 780 bp, encoding 260 amino acids and containing the conserved PGRP and Ami_2 structural domains. HdhPGRP-SC2-like gene as a short type PGRP had high similarity with the closely related species PGRP of mollusks. qPCR analysis showed that HdhPGRP-SC2-like mRNA was expressed in all tissues of the disk abalone, with the maximal expression level in gill, a certain amount of expression level in mantle and digestive gland, and the minimal content in foot and hemocyte. The prokaryotic expression vector pET-28a(+)-HdhPGRP-SC2-like was further constructed, and the recombinant protein rHdhPGRP-SC2-like gene was obtained by induction of expression, isolation, and purification. The recombinant protein had peptidoglycan binding activity and showed amidase activity in the presence of Zn2+. The finding indicated that HdhPGRP-SC2-like gene binded bacterial peptidoglycan components and played an important role in the immune defence against invading bacteria.
  • Occurrence and health risk assessment of organophosphate ester flame retardants in fishery products from Honghai Bay
    ZENG Yimei, LIU Qi, KE Changliang, DUAN Xingxing, YANG Hongliang, HUANG Ke, GU Xiaoli, ZHANG Ankai, CHEN Jiewen
    Journal of Dalian Ocean University. 2024, 39(1): 83-91. https://doi.org/10.16535/j.cnki.dlhyxb.2023-150
    Abstract (1640) PDF (497) HTML (1)   Knowledge map   Save
    In order to evaluate the quality and safety of fishery products caused by the contamination of organophosphate esters (OPEs), contents of 10 types of OPEs were determined in fishery products including 7 species of fish cultured in cages and 16 species of wild fish collected from fishing ports in Honghai Bay by Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS). The results showed that the average contents of ∑10OPEs were (55.8±24.2)ng/g (dry weight) in cultured species, significantly higher than those in wild fish (20.5 ng/g±20.6 ng/g, dry weight) (P<0.05). There was significantly higher content of ∑10OPEs in demersal fish (28.4 ng/g±22.6 ng/g, dry weight) than in pelagic fish (7.4 ng/g±4.3 ng/g, dry weight) in the wild fish (P<0.05). Tris (2-butoxyethyl) phosphate (TBOEP), tri-n-butyl phosphate (TNBP), tris (2-chloroisopropyl) phosphate (TCIPP), tris (2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPHP) were the organophosphate compounds with the highest frequency detected in the fishery products of Honghai Bay. The composition profiles of OPEs in cultured species were consistent with that in the demersal species, with the maximal levels of TCEP, TBOEP, and TCIPP, while the main OPEs in captured pelagic fishery products were TBOEP, TCIPP, and TPHP, in that order. The results of the exposure assessment showed that the non-carcinogenic risks and carcinogenic risks of OPEs in fishery products in the Honghai Bay for males and females in different age groups were below the potential risk thresholds and the health risks were acceptable to date. The finding indicates that OPEs is prevalent in farmed and wild caught fishery products, and that the level of health risk posed is still within the safe range. However, as the usage of OPEs continues to increase, it is recommended that the contamination of fish products with OPEs be continuously monitored.
  • Screening and verification of microsatellite markers associated with growth traits in Nile tilapia (Oreochromis niloticus)
    LIU Zhigang, GAO Fengying, TONG Yannan, YI Mengmeng, WANG Miao, ZHU Hai, LU Maixin, KE Xiaoli, CAO Jianmeng
    Journal of Dalian Ocean University. 2023, 38(6): 925-934. https://doi.org/10.16535/j.cnki.dlhyxb.2023-075
    Abstract (1639) PDF (682) HTML (1)   Knowledge map   Save
    In order to screen growth-related microsatellite markers for breeding in Nile tilapia (Oreochromis niloticus), the relationship between the growth traits (body weight, total length, body length, head length, body height and body width)and genotypes was analyzed in four tilapia populations (Gaoyao F0 population, Gaoyao F1 population, Panyu population and Hainan population) by 29 microsatellite markers. The results showed that a total of 242 alleles were detected at the 29 microsatellite loci in Gaoyao F0 population, with mean allele number (Na) of 8.345, observed heterozygosity (Ho) of 0.621 and polymorphism information content (PIC) of 0.842. The PIC values of all the loci were found to be great than 0.5, indicating that the genetic diversity was in high level in Gaoyao F0 population. Six microsatellite markers (GM114, GM213, GM423, GM642, UNH130 and UNH985) had significant correlation with more than one growth trait in Gaoyao F0 population (P<0.05), in which four microsatellite markers (GM213, GM642, UNH130 and UNH985) were significantly correlated with the growth traits in Gaoyao F1 population (P<0.05).It was found that these markers were genetically stable in different generations. The validation of the preliminary screening growth-related microsatellite markers in two out groups (Panyu population and Hainan population) revealed that four loci (GM213, GM642, UNH130 and UNH985) and three loci (GM642, UNH130 and UNH985) showed significant difference in growth traits among different genotypes in Panyu population and Hainan population (P<0.05). In conclusion, GM642, UNH130 and UNH985 were shown to be significantly correlated with growth traits of tilapia in different generations and populations. Tilapia with DD and HH genotypes of GM642, AD, BC and FF genotypes of UNH130, and GH and CF genotypes of UNH985 have obvious growth advantage, which can be regarded as candidate markers for Nile tilapia growth.
  • Design and test of flexible gripping device used in sorting for Yesso scallop (Patinopecten yessoensis)
    CAI Weiguo, MENG Delong, GUO Shenghan
    Journal of Dalian Ocean University. 2023, 38(6): 1044-1051. https://doi.org/10.16535/j.cnki.dlhyxb.2023-129
    Abstract (1632) PDF (645) HTML (2)   Knowledge map   Save
    In order to solve the practical problem of low efficiency and high damage rate in traditional sorting methods for marine treasures in production, a three finger flexible grasping device was developed based on the morphological and physical characteristics of Yesso scallop (Patinopecten yessoensis). The flexible fingers are in an “A”shaped structure, with the opening degree of Ф14.66-197.44 mm, which can meet the sorting needs of most precious shellfish. A flexible finger model, simplified Patinopecten yessoensis entity as a spherical object, was established and the force exerted on the flexible single finger and the flexible three finger grasping were simulated and analyzed. The results showed that the flexible single finger of sorting device bended towards the force side of the contact surface, and the flexible three fingers bended and deformed to form a complete envelope surface, when it was subjected to force, with good adaptive envelope performance. The success rate and clamping force of single size Yesso scallop were tested by building an experimental platform. The results showed that the success rate of grasping was found to be below 90% at air pressure of below 0.2 MPa. At the air pressure of 0.6 MPa, however, the average success rate of grasping was shown to be over 98%, without the damaged shell and edges. As the air pressure increased, the success rate of grasping and the change in clamping force were positively correlated. The gripping performance tests in Yesso scallop with three different body weights at air pressure of 0.6 MPa revealed that there was the maximum gripping force of 8.76 N in the transverse direction and 7.24 N in longitudinal direction. The shell and edges of Yesso scalop were undamaged, and the gripping force showed a decreasing trend as the body weight of Yesso scallop increased. The findings indicate that the sorting device designed in this article can meet the sorting needs of most shellfish treasures and can be applied to the non-destructive sorting of various shellfish treasures including scallops, oysters, abalones, and snails in large-scale production.
  • Research progress on shell-meat separation technology of shelled aquatic products:a review
    ZHAO Yu, ZHU Xu, ZHU Jianping, ZHAO Jiabin, FANG Guoai
    Journal of Dalian Ocean University. 2023, 38(6): 1083. https://doi.org/10.16535/j.cnki.dlhyxb.2023-059
    Abstract (1624) PDF (701) HTML (2)   Knowledge map   Save
    As the production of shelled aquatic products increases year by year, the traditional sales and manual processing mode (fresh sale, drunkenness and manual shelling) can no longer alleviate the contradiction of oversupply in the market. Automated deep processing of shelled aquatic products can improve the processing efficiency and ensure the health of workers and food safety, thus promoting the high-quality development of fisheries in China. Shell-meat separation technology is a prerequisite for deep processing of shelled aquatic products, and it is important to promote the development of deep processing equipment for shelled aquatic products. This paper reviews different methods of shell meat separation for shelled aquatic products, and classifies shell meat separation into pretreatment and shell removal technologies, analyzing and summa rising the research on several pretreatment technologies including heating and cooling pretreatment, enzyme pretreatment, ultra-high pressure pretreatment and combined pretreatment, and several shell removal technologies such as cutting, extrusion, centrifugation and high-pressure water jetting. In view of the deficiencies in the process of shell-meat separation of shelled aquatic products, it is proposed that large-scale processing equipment, automation and intelligence should be further developed and the research and development of shipboard processing equipment and crab deep processing should be strengthened. This review will provide ideas and references for further research on automatic processing equipment of shelled aquatic products.
  • Killing effect of ozone on Aeromonas hydrophila in aquaculture tailwater
    KE Ruilin, XU Huimin, CHEN Xi, MENG Shunlong, HU Gengdong, LI Dandan, QIU Liping, SONG Chao, FAN Limin, REN Lihua
    Journal of Dalian Ocean University. 2023, 38(6): 1013-1019. https://doi.org/10.16535/j.cnki.dlhyxb.2023-176
    Abstract (1605) PDF (699) HTML (1)   Knowledge map   Save
    To improve ozone disinfection process and optimize high efficiency disinfection technology of tailwater in aquaculture, different concentrations of ozonated water were prepared by regulation of generation period of an ozone generator, concentration and exposure period (1 and 10 min) of ozone neutralizer, and the sterilizing effect of ozonated water against different concentrations of Aeromonas hydrophila was determined by suspension quantification method under different stress times. The sterilizing effect was compared with the conventional disinfectant potassium persulfate. The results showed that the sterilization rate was found to be 92.66% at 6.4×105CFU/mL, 84.00% at 7.5×106CFU/mL, 80.67% at 1.5×107 CFU/mL and 79.58% at 3.2×108 CFU/mL with 1.2 mg/L ozone for 2 min, and 100%, 99.72%, 99.96% and 99.98% for 6 min, while the sterilization rate was 100% when potassium persulfate at 400 mg/L was used for 6 min, and the actual effects of ozone treatment of bacterial culture tail water were also tested. The findings indicated that the sterilization efficiency of ozone was much higher than that of potassium persulfate, with the optimal concentration of 1.2 mg/L, and the action time of 6 min, indicating that ozone sterilization rate for A.hydrophila was correlated with number of bacteria, concentration of ozone, and active time.
  • Effects of water temperature on gastric evacuation rate of mandarin fish Siniperca chuatsi fed formulated diet
    WANG Fubao, DONG Junjian, SUN Chengfei, WANG Miao, CHENG Guangzhao, LU Maixin, YE Xing
    Journal of Dalian Ocean University. 2023, 38(6): 1003-1012. https://doi.org/10.16535/j.cnki.dlhyxb.2023-090
    Abstract (1569) PDF (634) HTML (3)   Knowledge map   Save
    In order to investigate the effects of water temperature on gastric emptying rate of mandarin fish (Siniperca chuatsi) fed formulated diet to determine the appropriate feeding frequency, two sizes of mandarin fish with body weight of (89.50±10.21)g and (246.65±11.34)g were reared in 0.5 m3 glass fiber reinforced plastic buckets and fed formulated diet at water temperatures of 18, 25, and 30 ℃. The moisture, wet and dry mass of the gastric contents were measured in the mandarin fish anesthetized by anesthetic MS-222 at 0, 2, 4, 6, 8, 12, 18, 30 and 48 h after satiation, and linear, exponential and square root mathematical models were used to fit the relative wet and dry mass of the gastric contents at different time to screen the optimal gastric emptying model and to calculate the optimal feeding frequency. The results showed that the moisture of gastric contents in both size fish was found to be increased rapidly at first, then increased slowly and remained stable, while the dry mass of gastric contents to be decreased continuously, with a trend of rapidly decrease (0-8 h) and then slow down (8-48 h) at different temperatures. The relative wet and dry mass of fish gastric contents in the same size fish were negatively correlated with temperature (18 ℃ group >25 ℃ group >30 ℃ group). At different temperatures, the nearly empty time or completely empty time of the gastric contents of all the groups were 48 h, except 30 h in the small size fish at 30 ℃. The variance analysis showed that the fish size had significant influence on gastric evacuation of the relative wet and dry gastric contents (P<0.01). Temperature also had significant effects on gastric content moisture, relative wet and dry mass (P<0.01), without interaction between size and temperature (P>0.05). There was more accurately fitting model reflecting the gastric emptying by dry mass than by wet mass, and the exponential model was shown to be more suitable to describe the gastric emptying characteristics of mandarin fish. The fitting model showed that the gastric emptying of 80% dry mass in small size fish took 17.43 h at 18 ℃, 12.70 h at 25 ℃ and 9.71 h at 30 ℃, 20.40 h, with at 18 ℃, 15.74 h at 25 ℃ and 13.19 h at 30 ℃ in large size fish. The gastric emptying time was found to be decreased with the increase in warming temperature while prolonged with the increase in fish size. It is suggested that the feeding frequency practically be reduced to once a day or even lower in winter due to low water temperature, and to increase to 2 to 3 times/d in summer. At the same water temperature, however, better aquaculture benefits can be obtained by appropriately increasing the feeding frequency for small size fish and decreasing the feeding frequency of large size fish.
  • Protective effect of phillygenin (PHI) on liver injury induced by microcystins (MCs) in loach (Paramisgurnus dabryanus)
    RUAN Weilin, BI Xiangdong, DONG Shaojie, YOU Hongzheng, ZHANG Dajuan, QIN Genghua, ZHANG Chunxin, DAI Wei
    Journal of Dalian Ocean University. 2023, 38(6): 980-986. https://doi.org/10.16535/j.cnki.dlhyxb.2023-078
    Abstract (1568) PDF (602) HTML (1)   Knowledge map   Save
    In order to investigate the protective effect of phillygenin (PHI) on liver injury induced by subchronic toxic concentration of microcystins (MCs), loach (Paramisgurnus dabryanus) with body weight of (100.13±5.23)g were intraperitoneally injected with 17 μg/kg (body weight) MCs on the first day, and then successively injected with different concentrations of PHI [cumulative dose of 0.3, 0.6, 1.2 and 2.4 mg/kg (body weight)] on the following 3 days. On the sixth day, livers of P.dabryanus were taken to compare the histopathologic changes, alanine aminotransferase (ALT) activity, oxidative damage related indices [malonaldehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), glutathione reductase (GR)] and inflammatory factors [interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α)] of liver tissue. It was found that MCs induced histopathologic injury in liver. There was significant increase in ALT activity, the contents of MDA, and IL-1β and (TNF-α) 2 inflammatory factors in MCs group compared with the control group (P<0.05), while there was significant decrease in activities of 3 antioxidant enzymes in MCs group (P<0.05). The injection of PHI alleviated the MCs-induced histopathologic injury in liver, significantly decreased ALT activity, MDA content and 2 inflammatory factors levels (P<0.05), and significantly increased in the activities of SOD, GSH-PX and GR (except 0.3 mg/kg PHI) (P<0.05) compared with the MCs group. PHI alleviated the histopathologic and physiology function injury, oxidative damage and inflammatory response in liver, and had a protective effect on liver injury induced by MCs.
  • Research progress on the mechanism of carotenoid absorption, metabolism and deposition in animals in aquature: a review
    ZHANG Lili, WANG Guodong, HUANG Shiyu, GONG Xiaoting, WANG Yilei
    Journal of Dalian Ocean University. 2023, 38(6): 1072-1082. https://doi.org/10.16535/j.cnki.dlhyxb.2023-053
    Abstract (1566) PDF (775) HTML (1)   Knowledge map   Save
    Carotenoids are natural pigments commonly found in nature and play an important role in the growth, development, immunity, and body color of animals in aquaculture. The absorption, metabolism, and deposition ability of carotenoids animals in aquaculture is a key target for genetic improvement, which plays an important role in improving their traits. The main types, absorption, and metabolic molecular mechanisms of carotenoids is reviewed tin animals in aquaculture, with a focus on the function analysis of SR-B1, CD36, BCO1, BCO2, CYP2J19 and CYP3A80.The possible mechanisms of carotenoid ketosis and the characteristics of major carotenoid binding proteins are analyzed. Four research aspects are proposed to provide scientific reference for future research on the absorption, metabolism and deposition mechanism, including gene phenotype association analysis to reveal genetic basis, multiomics conjoint analysis to screen and identify new ketolase genes, single-cell RNA (ScRNA) sequencing to analyze carotenoid deposition process, and screening and construction of body color genetic strains.
  • Observation of early development and determination of the point of no return (PNR) in Chinese hook snout carp (Opsariichthys bidens)
    XING Yuxin, LUO Xiaonian, LI Jiao, DUAN Youjian, JI Chenyue, CHANG Jiantai
    Journal of Dalian Ocean University. 2023, 38(6): 972-979. https://doi.org/10.16535/j.cnki.dlhyxb.2023-094
    Abstract (1558) PDF (616) HTML (1)   Knowledge map   Save
    In order to probe into the developmental characteristics of early development and to determine the point of no return (PNR) in Chinese hook snout carp (Opsariichthys bidens), the morphological characteristics of early development and the effects of starvation on the growth, morphology and behavior were investigated in Chinese hook snout carp larvae from 1 day post hatching (dph) to 43 dph juveniles at water temperature from 20.5 ℃ to 26.0 ℃. The newly hatched larvae derived from artificial breeding were reared indoor and 9 dph postlarvae were reared and fed zooplankton in a 0.67 hm2 pond to observe the developmental characteristics and to determine the PNR. The results showed that 10 days old Chinese hook snout carp had initial feeding, with the mixed nutrition from 10 to 11 days old, completely exhausted yolk sac at 12 days old, and the first scales at 27 days old, fully covered scales at 43 days old. Thus, the Chinese hook snout carp larvae were divided into early fry (from 0 day old to 11 days old), late fry (from 12 to 26 days old), and juvenile stages (27 to 43 days old). The starvation and re-feeding test revealed that Chinese hook snout carp larvae had PNR at 12 days to 13 days old, and all died at 14 days old under starvation stress at water temperature of (21.5±1.0)℃. The finding indicated that Chinese hook snout carp as a fish species with late exhaustion of yolk sac was benifit to better adapt to the ecological environment in the wild, and that Chinese hook snout carp had only 2 d mixed nutrient period, and needed to be stocked into the pond at the right time, so as to improve the survival rate of the fry.
  • Isolation,identification and drug sensitivity of Pseudomonas veronii from diseased half smooth tongue-sole (Cynoglossus semilaevis Günther)
    LIN Baozhu, ZHAO Lu, WANG Haoyi, HAN Zhuoran, SUN Jingfeng
    Journal of Dalian Ocean University. 2023, 38(6): 987-993. https://doi.org/10.16535/j.cnki.dlhyxb.2023-092
    Abstract (1533) PDF (608) HTML (3)   Knowledge map   Save
    In order to investigate the pathogenesis of diseased half smooth tongue-sole (Cynoglossus semilaevis Günther), a bacterial strain was isolated from the liver of the diseased half smooth tongue-sole with body weight of 20 to 40 g, designed as CLPV-114, and identified by morphological observation, physiological, and biochemical features and the sequence analysis of 16S rRNA. The drug sensitivity, artificial infection, histopathological examination and determination of growth curve were examined in the strain CLPV-114. The median lethal dose was determined and histopathological observations were conducted in the artificial infection test. The results showed that the strain CLPV-114 was gram-negative bacterium, and closely related to Pseudomonas veronii (AF064460) and Pseudomonas veronii (AY144583), so identified as Pseudomonas veronii. The drug sensitivity test showed that CLPV-114 was highly sensitive to 18 kinds of drugs including amoxicillin, ampicillin, cefoperazone, moderately sensitive to 11 antibiotics such as nitrofurantoin, azithromycin, tetracycline, and resistant to antibiotics such as cefixime, sulfafurazole and sulfamethoxydiazine. Infection test showed that the clinical symptoms were similar to those of naturally diseased fish, with the LD50 of 1.3×107 CFU/mL in CLPV-114 against half smooth tongue-sole. Histopathological observations found that CLPV-114 strain caused obvious histological damage, such as hepatocellular tissue necrosis, vascular congestion of the central filament vessel of gill, haemorrhage and deposition of hemosiderin in the spleen, and the shedding of the intestinal villi. The finding indicates that the strain CLPV-114 isolated from the liver of diseased tongue sole is Pseudomonas veronii, which has strong pathogenicity to tongue sole and can cause significant pathological changes in different tissues, and provides an effective scientific reference for control of Pseudomonas veronii disease in half smooth tongue-sole.
  • Effects of exogenous addition of outer membrane vesicles on biofilm formation of Pseudoalteromonas marina and settlement of mussel (Mytilus coruscus)
    WU Guanju, MIAO Tianyin, HU Xiaomeng, ZHANG Wen, YANG Jinlong, LIANG Xiao
    Journal of Dalian Ocean University. 2023, 38(6): 994-1002. https://doi.org/10.16535/j.cnki.dlhyxb.2023-097
    Abstract (1525) PDF (585) HTML (1)   Knowledge map   Save
    To investigate the effects of outer membrane vesicles (OMVs) on the biofilm formation of Pseudoalteromonas marina and the settlement of mussel (Mytilus coruscus) plantigrades with shell length (0.88 mm±0.16 mm) and shell height of (0.55 mm±0.12 mm), OMVs were extracted and purified from P.marina and added into P.marina bacterial fluid to form biofilms, and the inducing capacity of biofilms on the settlement of mussel juveniles was detected at the final OMVs concentration of 0.1, 1, 10 and 20 μg/mL. The results showed that OMVs were successfully extracted from P.marina, with the more content of OMVs extracted from the bacterium than that in the supernatant. The biofilms had the maximal inducing activity to mussel plantigrades, with the settlement rate of 56.42% at the OMVs concentration of 10 μg/mL. With the increase in OMVs concentration, the bacterial density and biofilm thickness of biofilms were found to be increased, with increase in α-polysaccharides, β-polysaccharides, lipids and proteins in extracellular products. Correlation analysis showed that the lipid content in the biofilms was significantly correlated with mussel settlement (P<0.05), indicating that addition of OMVs promoted the formation of P.marina biofilms and increases the content of extracellular products of biofilms. It is speculated that the improvement in inducing ability of biofilmd to mussel settlement after adding OMVs is primarily due to the increase in lipid content.
  • Finite element analysis of damage characteristics of fishing vessels in collision between merchant and fishing vessels
    LI Mengyang, XU Shuo, DUAN Ruoheng, SHI Xufang
    Journal of Dalian Ocean University. 2023, 38(6): 1052-4062. https://doi.org/10.16535/j.cnki.dlhyxb.2023-180
    Abstract (1521) PDF (618) HTML (1)   Knowledge map   Save
    In order to investigate the impact of various collision conditions on the damage characteristics of a large merchant vessel colliding with a fishing vessel, referred to as a commercial fishing vessel collision, the collision process was simulated in a typical 42 m fishing boat as an example, and under collision conditions of different collision angles, speeds, and masses, using finite element method and LS-DYNA software, resulting in stress-strain cloud maps and energy curves for the hull damage of the fishing boat. The variation law of damage characteristics of the fishing vessel with collision conditions was obtained through analysis. The results indicated that there was the maximal damage degree in the collided fishing boat at the speed of 8 m/s in the merchant ship and at the collision position in the middle of the cabin, resulting in broken hulls and fractured skeletons under the conditions in present study. The vessel experienced both vertical force and force along the direction of captain at the collision angle of 60°, leading to the largest hull fracture. While a merchant ship weighing 10 000 tons caused the most severe hull damage, when the weight exceeded 10 000 tons and there was a significant tonnage gap between the ship and the fishing boat, increasing mass had little effect on the extent of damage of fishing boat. The findings indicate that finite element simulation methods can be employed to analyze the structural damage of commercial fishing boats during collisions. In commercial fishing vessel collisions, factors such as mass, collision speed, angle, and position of merchant vessels significantly influence the damage degree of fishing vessels, with collision speed, mass, and other factors positively correlating with damage severity.
  • Effects of substrate material and particle size on survival, growth and microbial community of whelk (Babylonia areolata)
    HUANG Ruipin, ZHANG Lei, ZHANG Weixiao, LIU Mingyuan, SUI Changrun, WANG Baolong, LIU Ying, ZHANG Qian
    Journal of Dalian Ocean University. 2024, 39(1): 57-65. https://doi.org/10.16535/j.cnki.dlhyxb.2023-168
    Abstract (1458) PDF (500) HTML (1)   Knowledge map   Save
    To explore the appropriate substrate for outdoor cement pond cultivation of whelk (Babylonia areolata), the whelk with body weight of (4.692±1.033)g were reared in a rectangular culture pond of 3.6 m in length×1.4 m in width×1.0 m in height with 12 cm-high plastic screw frame covered with a 245 μm sieve silk mesh at bottom of the pond at stocking density of 480 individuals/m3 at water temperature of (30.2±2.7)℃. Sea sand (group SS), fine ceramsite with particle size of 1.0-2.0 mm (group FC), coarse ceramsite with particle size of 2.0-4.0 mm (group CC) and sea sand (50%)+ coarse ceramsite (50%)mixture (group SS+CC) were disposed on the 245 μm sieve silk mesh at a thickness of 5 cm in the test ponds to investigate effects of substrate material and particle size on the survival and growth of B.areolata, water quality and substrate microbial community. The results showed that there was over 90% of survival rate in B.areolata under the four sediment conditions, without significant difference among groups(P>0.05). The maximal specific weight growth rate was observed in group FC (1.386 4 %/d±0.219 6 %/d), significantly higher than that in groups CC, SS and SS+CC (P<0.05). The structure and composition of microbial community were varied with different substrates, with the minimal richness and diversity in group SS, and higher richness and diversity in group FC. There were higher relative abundances of Proteobacteria, Planctomycetes, Bacteroidetes and Acidobacteriota in group FC at phylum level, with lower relative abundance of Vibrio and higher relative abundance of Exiguobacterium and Halomonas in both group FC and group SS+CC. The fine ceramsite had positive effect on resisting pathogenic Vibrio and preventing water quality deterioration. The results of microbial function prediction indicated an increase in relative abundance of pathways associated with various microbial substance metabolisms in the group FC. Also, the substrate led to affect the water quality during aquaculture, with lower concentration of  in group CC than that in group FC (P<0.05). The findings indicated that utilization of fine ceramsite as the substrate material in outdoor cement ponds for B.areolata cultivation promoted body weight growth, inhibited the growth of pathogenic microorganisms, and contributed to the water purification in aquaculture ponds at certain level.
  • A review of harvest strategy approaches in fisheries:theory, applications and future challenges
    ZHU Jiangfeng
    Journal of Dalian Ocean University. 2024, 39(1): 1-8. https://doi.org/10.16535/j.cnki.dlhyxb.2024-037
    Abstract (1404) PDF (966) HTML (4)   Knowledge map   Save
    Traditional methods of fisheries stock management decision-making have been developed since the 1950s to collect data and assess the status of stock, make scientific management recommendations and implement management measures through management measures. The disadvantage of traditional methods is that stock assessment often has large uncertainties, resulting in management recommendations that also have large uncertainties. Beginning in the 1980s and 1990s, with the development of computer simulation technology, the application of harvest strategy (management procedure) methodology in fisheries management has continued to develop, and has now evolved into a relatively mature and complete set of quantitative fisheries stock management methodology system, and plays an important role in the protection of marine mammals and the development and conservation of economic fish stocks. Comparatively speaking, the harvest strategy approach has been less applied and studied in China. This paper summarizes the basic process of traditional fishery resource management decision-making, as well as the characteristics, advantages and challenges of the harvest strategy approach, and proposes that the application of the harvest strategy is conducive to the scientific management and long-term sustainable use of fishery resources under the premise that specific management measures can be effectively implemented. With regard to fisheries that are considering the use of management strategy evaluation to establish harvest strategies, recommendations for future development are put forward, such as strengthening the collection of basic data on fisheries and population biology, strengthening research on population simulation techniques and capacity-building, and accelerating the development and application of new harvest strategies applicable to severely declining stocks, with a view to providing a reference for China in applying the harvest strategy approach to fisheries management decision-making.
  • Analysis of phytoplankton community characteristics and influencing factors in the Yangtze River Estuary
    SHAO Haiyan, WANG Qing, GAO Chunxia, ZHAO Jing
    Journal of Dalian Ocean University. 2024, 39(1): 124-133. https://doi.org/10.16535/j.cnki.dlhyxb.2023-171
    Abstract (1396) PDF (667) HTML (1)   Knowledge map   Save
    In order to understand the composition and structural characteristics, spatiotemporal distribution pattern and key impact drivers of phytoplankton communities in the Yangtze River Estuary, the characteristics of phytoplankton communities and the relationship between the characteristics of phytoplankton communities and influencing factors were explored based on the survey data of phytoplankton in the Yangtze River Estuary in August (summer) and November (autumn) from 2018 to 2020 by community diversity analysis indicators and generalized additive model (GAM). The results showed that a total of 185 species of phytoplankton were collected in 8 phyla, 99 genera, with the dominant species mainly including Skeletonema costatum, Aulacoseira granulata, Melosira sulcata, Cyclotella sp. and Chlamydomonas sp., and the main phytoplankton groups including Bacillariophyta, Cyanophyta and Chlophyta, in which Skeletonema costatum had long been overwhelming. There were significantly higher abundance and species of phytoplankton in summer than those in autumn (P<0.05). In autumn, however, phytoplankton communities showed higher diversity index and richness index and more evenly distributed. Spatially, the average phytoplankton abundance showed the distribution pattern of East Beach >South Branch >North Branch as a whole. The GAM analysis indicated that water temperature (Tem), pH and total nitrogen to total phosphorus ratio (TN/TP) were the environmental factors (P<0.05) significantly affecting the abundance distribution of phytoplankton in the Yangtze River Estuary in summer, with the maximal contribution rate of 71.86% from TN/TP. Salinity (Sal), dissolved oxygen (DO) and chemical oxygen demand (CODMn) were found to be the environmental factors (P<0.05) significantly affecting the abundance distribution of phytoplankton in the Yangtze River Estuary in autumn, especially the DO contribution up to 48.48%. The findings indicate that there are seasonal differences in the community composition, structure, pattern and influencing factors of phytoplankton in the Yangtze River Estuary, which provides references for understanding of the dynamics of phytoplankton resources in the Yangtze River Estuary.
  • Research progress on type Ⅵ secretion system (T6SS) and its hemolysin coregulatory protein from pathogenic bacteria in aquatic animals:a review
    WU Shuilong, HUANG Yu, WANG Bei, TANG Jufen, CAI Jia, JIAN Jichang
    Journal of Dalian Ocean University. 2024, 39(1): 162-171. https://doi.org/10.16535/j.cnki.dlhyxb.2023-095
    Abstract (1326) PDF (705) HTML (0)   Knowledge map   Save
    Type Ⅵ secretion system (T6SS) as a protein secretion system exists within varieties of gram-negative bacteria,and plays important roles in virulent factors release, biofilm formation, iron ion uptake, vesicular transport and environmental pressure adaptability, which is crucial for the pathogenesis of aquatic bacterial pathogens such as Vibrio parahaemolyticus, V.alginolyticus, V.harveyi, Aeromonas hydrophila, and Edwardsiella tarda. However, the reports regarding the components and functions of T6SS from aquatic pathogenic bacteria are still rare. The latest research progress on biological functions, regulatory mechanisms of T6SS, as well as the biological roles, evolutionary relationships of the key regulator of T6SS-hemolysin coregulatory protein (Hcp) is summarized from several aquatic bacterial pathogens. Several future key directions are proposed including new biofunctional discoveries of T6SS, correlation between T6SS activity and environmental factors, the regulation between T6SS and virulence-related metabolism. This review will help researchers better understand the roles of aquatic animal pathogens T6SS and provide new ideas for further research on pathogenic mechanism and control of bacterial diseases in aquaculture.
  • Analysis of dynamic characteristics of turning movement of juvenile grass golden fish based on PIV technology
    ZHANG Juan, ZHANG Ying, HUANG Xiaoshuang, LIU Bilin, CHEN Xinjun, KONG Xianghong, CHEN Jiaqi
    Journal of Dalian Ocean University. 2024, 39(1): 92-100. https://doi.org/10.16535/j.cnki.dlhyxb.2023-165
    Abstract (1318) PDF (495) HTML (0)   Knowledge map   Save
    In order to understand the propulsion mechanism and propulsion performance of ornamental fish in the state of turning motion, the juvenile grass golden fish (Carassius auratus) with body length of 5-8 cm was taken as the research object, and the changes of the fluid flow field of the maneuvering motion were tracked by particle image velocimetry (PIV) and vorticity moment theorem, and the motion characteristics and dynamic characteristics of the tail of the juvenile fish during the turning process were analyzed. The results showed that the morphological structure of the juvenile C-shaped and S+C-shaped mainly changed during the turning process, and the positive and negative vorticities of the flow field around the tail of the juvenile fish appeared alternately during the turning process. When the body morphology of the fish is C-shaped and turned, the average velocity of the juvenile is 0.130 7 m/s, and the positive force of the fluid on the tail of the juvenile fish is 2.06 mN to 133.49 mN, and the negative force is -83.85 mN to -2.15 mN. When the body morphology of the fish is S+C structure, the average velocity of the juvenile is 0.104 4 m/s, and the positive force of the fluid on the tail of the juvenile fish is 24.06 mN to 80.95 mN, and the negative force is -59.60 mN to -5.86 mN. The results show that when turning, the maneuverability of the fish body shape with C-shaped structure change is better than that of fish body shape with S+C structure change, and the time of force peak is different for different turning types.
  • Analysis of denitrification capacity and microbial community of biofilms with different fillers in mariculture wastewater
    CHEN Xiaohong, XU Yibin, LIN Yongqing, QIU Denggao, JIANG Shuangcheng, ZHENG Huidong
    Journal of Dalian Ocean University. 2024, 39(1): 9-19. https://doi.org/10.16535/j.cnki.dlhyxb.2023-153
    Abstract (1314) PDF (647) HTML (0)   Knowledge map   Save
    To investigate the nitrogen removal capacity of different filler-biofilms in mariculture tail water, biofilters were constructed by the addition of oyster shells (M), coral stones (S), suspended ball fillers (F), elastic fillers (T), and without any filler as control (C), respectively. The formation speed and the biomass of biofilms as well as the nitrogen removal capacity of the biofilms at 24 hours were compared, while the changes in microbial community structure of the biofilms on biofilters were analyzed using Illumina Miseq high-throughput sequencing technology during biofilms formation period(20th day, 40th day, and 60th day). The different filler-biofilms were found to required 46-50 days for mature, with most rapid formation of the coral stone filler biofilm. Scanning electron microscopy showed that the biofilms on elastic filler and suspended ball filler had more biomasses than the other two fillers, largely consisting of rod-shape bacteria. The analysis of nitrogen removal capacity at 24 hours showed that there was the maximal removal rate of ammonia nitrogen and nitrate nitrogen by suspended ball fillers, and that the maximal removal rate of nitrite nitrogen by coral stone, which were (68.66%±6.27%), (6.73%±3.41%), and (99.99%±0.00%), respectively. The analysis of microbial community diversity revealed that the abundance of bacteria on elastic filler biofilms was increased, while the diversity of bacteria on oyster shell and coral stone biofilms was decreased significantly with the prolongation of biofilms formation time (P<0.05). The dominant microfloras of biofilms with different fillers were shown to be Proteobacteria and Bacteroidetes at the phylum level. The relative abundances of Nitrospirae and Nitrospinae were increased with the extension of biofilms formation time. Nitrosomonas, Nitrospira, Nitrospina and unclassified_Nitrosomonadaceae were the dominant bacteria with nitrification on different filler-biofilms at the genus level. The descending order of relative abundance of nitrifying bacteria at 60th day was described as: suspended ball fillers (42.53%)> oyster shells (30.50%), elastic fillers (29.30%)> coral stones (11.74%)(P<0.05). The relative abundance of denitrification bacteria, such as Pseudomonas, Ralstonia, Chitinophaga and Herbaspirillum, were higher on the biofilms of coral stone than on other filler-biofilms. The findings indicated that coral stone and suspended ball filler as ideal fillers were favorable to enrichment of nitrogen removal bacteria, and had better denitrification ability for mariculture wastewater.
  • Seasonal differences and functional group characteristics of plankton community structure in Cetian Reservoir in Shanxi Province
    GENG Zhiyuan, ZHAO Lele, JIA Xin, HU Yafei, LIU Shaozhen, LIU Qing, SONG Jing
    Journal of Dalian Ocean University. 2024, 39(1): 101-113. https://doi.org/10.16535/j.cnki.dlhyxb.2023-175
    Abstract (1305) PDF (528) HTML (0)   Knowledge map   Save
    In order to evaluate the seasonal differences and functional group characteristics of plankton community structure in Cetian Reservoir in Shanxi Province, in the Haihe River, and contribute to reservoir protection and utilization,the characteristics of functional groups of plankton including species composition, biomass, density, spatial and temporal distribution, and their relationships with water environmental factors were investigated and analyzed in samples collected in Cetian Reservoir on October 12, 2020 (autumn), and March 27 (winter), June 21 (spring), and September 2 (summer), 2021. The results showed that 122 species of phytoplankton in 63 genera, 8 phyla, were identified, biomass and density were ranged from 7.31 mg/L to 45.69 mg/L and from 6 500.21 ind./L to 15 183.93 ind./L, with 30 functional groups of phytoplankton, including representative functional groups N, J and W1. A total of 21 species of zooplankton in 13 genera including 4 groups were identified, with biomass ranging from 1.49 mg/L to 25.53 mg/L and density varying from 2 128.90 ind./L to 17 699.72 ind./L. The zooplankton was divided into 9 functional groups, with representative functional groups RF and LCF. The average values of comprehensive trophic status index (TLI) were shown to be 53.45, 40.19, 52.66 and 48.87 in different seasons, with Shannon-Wiener diversity index (H′) of 0.80-1.54 and Pielou evenness index (J) of 0.17-0.32 in phytoplankton and 0.24-1.00 and 0.08-0.32 in zooplankton. There was Margalef index (d) of 12.81-16.18 in phytoplankton and 2.08-2.87 in zooplankton. The Simpson dominance Index (D) was 0.40-0.77 in phytoplankton and 0.10-0.54 in zooplankton. Pearson correlation analysis, Mental correlation analysis and redundancy analysis (RDA) showed that temperature, and contents of dissolved oxygen, phosphorus, nitrogen and chlorophyll a were the most important factors affecting the plankton community structure in Cetian Reservoir. The significant seasonal differences in species composition, functional group structure, biomass and density of plankton were observed in Cetian Reservoir, indicating that the water quality of Cetian Reservoir was in a state of heavy pollution, and that filter-feeding fishes are suggested to be stocked increasingly for control plankton population.
  • Kinetics on effect of Kuroshio axis meander on the resource recruitment of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean
    XU Zhixin, LI Yuesong, PAN Lingzhi, YU We, ZHANG Yu
    Journal of Dalian Ocean University. 2024, 39(1): 144-152. https://doi.org/10.16535/j.cnki.dlhyxb.2023-106
    Abstract (1299) PDF (446) HTML (0)   Knowledge map   Save
    In order to evaluate the effect of physical environment changes caused by the meander of the Kuroshio axis on the resource recruitment of neon flying squid (Ommastrephes bartarmii), the transport distribution and resource recruitment of the early life history stage (70 d) of the winter-spring cohorts of O.bartarmii were simulated in the Northwest Pacific Ocean by the physical model (FVCOM-Global ) coupled with the individual model (IBM). The correlation between the large and small meander paths and the resource recruitment of the squid was judged by using the southernmost point of the center of gravity of the Kuroshio main axis of 140°E in March, which was located south of 32°N. The results showed that there was an interannual fluctuation in the recruitment of the squid in the Northwest Pacific Ocean from 2007 to 2016, which was significantly correlated with the Kuroshio axis meander in March (R2=0.71). In other words, in the year of small meander, the larvae and juveniles of the squid were transported northward or northeastward, north of 25°N and east of 145°E. The higher the proportion of the neon flying squid larvae, and juveniles distributed in this sea area were, the higher the relative recruitment was, with a good positive correlation (R2=0.89). The Kuroshio warm current produced in the process was obvious in the sea area north of 25°N. When the flow rate was 0.2-0.6 m/s, the distribution of larvae and juveniles of the neon flying squid in the sea area was denser at average water temperature of 20.2 ℃ and the northerly isotherm. In the vertical distribution, there was a positive correlation between the vertical distribution and recruitment of different years (R2=0.65). The findings indicated that the meander of the Kuroshio axis in March was one of the key factors affecting the recruitment of neon flying squid resources, which also provides a scientific basis for predicting the abundance of the resources in that year.
  • Research progress on nutritional quality and influencing factors related to nutrients in abalone:a review
    WANG Teng, ZHAO Xinnan, LIN Yichen, SONG Dongru, HUO Shanqin, XUE Yong, TAN Zhijun, PENG Jixing
    Journal of Dalian Ocean University. 2024, 39(1): 172. https://doi.org/10.16535/j.cnki.dlhyxb.2023-112
    Abstract (1290) PDF (524) HTML (0)   Knowledge map   Save
    Abalone is a high-quality seafood with high nutritional and economic value, and rich in high-quality protein, amino acids, polysaccharides, polyunsaturated fatty acids, trace elements, and other nutrients and active ingredients. In recent years, with the increasing demand in the consumer market, the abalone industry has developed rapidly, and has become an important pillar of China’s mariculture industry, in addition to a small amount of culture in Liaoning and Guangdong, Fujian and Shandong are the main places of habitat. At this stage, the improvement of nutritional quality and traits has gradually become an important research direction in abalone culture. In this paper, the relevant research on the nutritional quality components of abalone are summarized, including the basic nutrients, flavors, and functional actives, focusing on the effects of factors such as species, origin, sampling season, culture method, diet and exogenous stresses on the nutritional quality of abalone. Due to the large number of factors and indicators of variation, and the lack of standardized criteria for evaluating the nutritional quality of abalone. It is urgent to carry out systematic research on abalone quality evaluation, as well as the control mechanism of abalone quality by diet, environmental factors, culture method, and processing mode, to provide scientific references for abalone culture, cultivation of new varieties, comprehensive evaluation of abalone quality, and mining of characteristic indices.
  • Complex relation extraction from health aquaculture standards based on an improved BiRTE model
    SONG Qishu, YU Hong, QIAO Shihan, LUO Xuan, LI Guangyu, SHAO Liming, ZHANG Sijia
    Journal of Dalian Ocean University. 2024, 39(1): 153-161. https://doi.org/10.16535/j.cnki.dlhyxb.2023-201
    Abstract (1278) PDF (534) HTML (1)   Knowledge map   Save
    A complex relationship extraction method for health aquaculture standards is proposed to address issues such as inaccurate recognition of domain-specific nouns and the complexity of semantics hindering entity relationship extraction based on an improved BiRTE model. The BiRTE model, which reduces error propagation through bidirectional extraction and exhibits strong relationship extraction capabilities, was adopted as the foundational model. To enhance the model’s information-extracting ability from texts of fisheries standard files, RoBERTa was used as the encoder encoding domain-specific nouns in fisheries standard files using whole-word masking and dynamic masking, enriching word vector information and enhancing feature representation. Thus, the Self-Attention is integrated to combine entity features and relationship features, focusing on strengthening the connection between entity extraction and relation prediction, thereby improving the accuracy of relation extraction. It was found that the proposed model achieved precision of 95.9%, recall of 95.4%, and F1 scores of 95.7% from the extraction of complex relationships in fisheries standards, representing an improvement of 4.2%, 3.1%, and 3.8%, respectively, compared to the original model. The finding indicates that the proposed improved BiRTE-based model, as an effective method for extracting complex relationships in fishing standards, can effectively address the problems of inaccurate identification of proper nouns and difficulty in extracting entity relationships due to semantic complexity in the field of fishing standard text relation extraction.
  • Numerical simulation of concentration distribution characteristics of ecological indicators in Liaodong Bay based on Delft3D model
    ZHAO Ziyu, ZHU Xiaosen, WANG Zhuo, ZHANG Mingliang
    Journal of Dalian Ocean University. 2024, 39(1): 134-143. https://doi.org/10.16535/j.cnki.dlhyxb.2023-133
    Abstract (1276) PDF (519) HTML (0)   Knowledge map   Save
    In order to explore the temporal and spatial distribution characteristics and interaction mechanism of chlorophyll a and nutrients in the Liaodong Bay, an ecological dynamic model is established including ecological indicators such as chlorophyll a (Chl-a), dissolved oxygen (DO), ammonia nitrogen  based on the numerical simulation method (Delft3D model), in Liaodong Bay based on Delft3D model. The accuracy of the model was verified, and then the spatial-temporal changes and distribution of ecological indicator concentrations including Chl-a in the Liaodong Bay waters were analyzed. The results showed that there were obvious spatial and temporal distribution characteristics of the ecological index concentrations in the Liaodong Bay. A trend of autumn (4.83 μg/L) >summer (4.13 μg/L) >spring (3.39 μg/L) in the concentration of Chl-a was observed, spring (9.41 mg/L) >summer (7.26 mg/L) >autumn (5.84 mg/L) in concentration of  was found, spring (0.76 mg/L) >autumn (0.56 mg/L) >summer (0.50 mg/L) in concentration of DO was occurred, spring (0.039 mg/L) >autumn (0.030 mg/L) >summer (0.026 mg/L) in the concentration of  was found and autumn (0.025 mg/L) >summer (0.020 mg/L) >spring (0.018 mg/L) in concentration of width=54,height=29,dpi=110 was observed. In terms of spatial distribution, the high concentration distribution of Chl-a, width=54,height=29,dpi=110 (spring and summer) and  (spring and summer) was found in the northeast Liaodong Bay and low in the southwest Liaodong Bay, and the concentration of  was high at the bayhead and baymouth and low in the middle. It was found that the important factors affecting the temporal and spatial distribution of ecological index concentrations were of Liao River and Daliao River at the upper basin of Liaodong Bay, with the relative limitation of phosphorus as nutrient limitation in the Liaodong Bay.
  • Correlation between otolith structure and early growth of Gymnocypris przewalskii larvae and juveniles
    WANG Yang, FANG Di’an, KUANG Zhen, TAN Longfei, LIANG Yidong, LUO Hui, QI Hongfang, XU Dongpo
    Journal of Dalian Ocean University. 2024, 39(1): 20-28. https://doi.org/10.16535/j.cnki.dlhyxb.2023-102
    Abstract (1267) PDF (607) HTML (1)   Knowledge map   Save
    In order to clarify relationship between structure of otolith and early growth characteristics in larval and juvenile Gymnocypris przewalskii, the microstructural characteristics was observed and the appearance time of the first rings and deposition pattern of the otolith rings were comparatively identified in larval otolith of cultured and wild G.przewalskii from artificial breeding and collected from Shaliu River (37°18′50.93″ N, 100°08′6.86″ E) and Quanji River (37°14′7.10″ N, 99°53′3.78″ E), the migratory spawning tributaries of Qinghai Lake. The otolith deposition was observed in the larvae and juveniles exposed to 10, 15, and 20 ℃ in temperature marking test and the correlations between the otolith daily age, width of otolith marking rings and daily age were fitted. It was found that the deposition of otolith diurnal cycle is daily. The larval fish daily age was calculated by the otolith rings number plus 1 (N+1). The daily age and sampling date revealed that the larvae and juveniles collected in Shaliu River in 2020 were incubated from June 5th to August 14th, peak in mid-July and early August. The larvae and juveniles in Quanji River were incubated from June 27th to August 3rd, the peak period in the mid-July. The results above were basically consistent with the fish larvae appearance time found in field investigation. The total length of larval and juvenile had significant linear, correlated with daily age, the otoliths length had significant linear correlated with fish total length with the maximal correlation coefficient in the artificially cultivated larvae and juveniles at water temperature of 15 ℃. The fitted equation was shown to be LT=0.167 2t+10.377(R2=0.689 0, P<0.001). The otolith growth of the larvae and juvenile was greatly affected by the environmental factors, and the variation of otolith deposition was closely related to the growth and development of larvae and juveniles.
  • Expression characteristics of CgLOX4 gene in larval development of Pacific oyster (Crassostrea gigas)
    HU Yue, LENG Jinyuan, SUN Jiejie, WANG Lingling, SONG Linsheng
    Journal of Dalian Ocean University. 2024, 39(1): 38-47. https://doi.org/10.16535/j.cnki.dlhyxb.2023-120
    Abstract (1265) PDF (569) HTML (3)   Knowledge map   Save
    To analyze the expression characteristics of CgLOX4 during larval development, the full-length cDNA sequence of LOX4 was amplified from Pacific oyster (Crassostrea gigas) by using PCR, and the expression characteristics of CgLOX4 in different stages of larval development were further analyzed by qRT-PCR and whole-mount immunofluorescence experiments. It was found that the CgLOX4 gene had full-length cDNA sequence of 1 862 bp with an open reading frame of 834 bp encoding 277 amino acids, with the isoelectric point of 8.36. The amino acid sequence of CgLOX4 gene contained a conserved HOX domain, and CgLOX4 gene was expressed in all the tested tissues of adult oyster, with significantly higher expression level in the adductor muscle than that in hepatopancreas, gills, hemolymph, gonad and labial palps tissue (P<0.05). CgLOX4 was expressed in all the examined early embryos, with relatively high expression level in fertilized eggs, and four-cells. The whole-mount immunofluorescence assay revealed that the positive signals of LOX4 were mainly distributed in the shell field of trochophore, the visceral mass of D-shape larvae and the digestive gland of umbo larvae. The findings indicate that CgLOX4 gene is one of the transcription factors activated earlier in the early development process of the oyster, and may play an important role in regulating the formation of larval shell and digestive organ.
  • Effects of bacterium-alga synergism on aquatic environment, growth and immunoenzymatic activities in largemouth bass (Micropterus salmoides) culture
    ZENG Tianyu, CHEN Xi, XU Huimin, MENG Shunlong, JIN Yuqin, HU Gengdong, LI Dandan, QIU Liping, SONG Chao, FAN Limin, XU Pao
    Journal of Dalian Ocean University. 2024, 39(1): 29-37. https://doi.org/10.16535/j.cnki.dlhyxb.2023-219
    Abstract (1258) PDF (602) HTML (2)   Knowledge map   Save
    In order to explore the effects of addition of green alga (Chlorella vulgaris), bacterium (Bacillus subtilis) and mixture of C.vulgaris and B.subtilis on aquatic environment, growth performance and related enzyme activities of largemouth bass (Micropterus salmoides), juvenile largemouth bass with body weight of (11.71±0.90)g was reared in a 1 000 L polyethylene barrel filled with 800 L water added with C.vulgaris (density of 1×109 cells/L at 6.25 mL/L)(alga group), B.subtilis (1×1011 CFU/g at 0.75 mg/L) (bacterium group), both C.vulgaris and B.subtilis (bacterium + alga mixture group), and blank (without any bacterium and alga, control group for days). The results showed that there were generally optimised physical and chemical indices in the water environment in the alga group and bacterium group during the experiment, compared with the blank group, with the relatively small differences in the total nitrogen, total phosphorus and dissolved oxygen contents in each experimental group, while there were considerably varied in the contents of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen, especially in the water environment in the bacterium + alga mixed group, with the minimal ammonia nitrogen, nitrate nitrogen and nitrite nitrogen contents in water in most time points (P<0.05). At the end of the experiment, the largemouth bass in all experimental groups had increase in body weight, weight gain rate, and specific growth rate compared with the blank group, with significant differences in only the bacterium + alga mixture group compared with the blank group (P<0.05). The hepatic glutathione (GSH) content, and activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and lysozyme (LZM) in general were shown to be significantly increased (P<0.05), and malondialdehyde (MDA) content to be significantly decreased (P<0.05), especially in the bacterium + alga mixture group compared with the blank group. To sum up, it can be seen that addition of either C.vulgaris or B.subtilis to the water environment can improve the water quality, promote the growth and hepatic antioxidant capacity and immunity in largemouth bass, and addition of both the green alga and bacterium at the same time is more effective.
  • SSR, SNP and InDel locus characteristics analysis in Gymnocypris eckloni based on transcriptome sequencing
    HE Caixia, LI Changzhong, JIN Wenjie, BAO Changhong, JIAN Shenglong, LI Zhaonan, WANG Linan, YAN Qingchun, WANG Zhenji, WANG Guojie, CHEN Yanxia
    Journal of Dalian Ocean University. 2024, 39(1): 48-56. https://doi.org/10.16535/j.cnki.dlhyxb.2023-164
    Abstract (1254) PDF (537) HTML (0)   Knowledge map   Save
    In order to utilize molecular markers for large-scale development and marker-assisted selection in breeding of Gymnocypris eckloni, the transcriptome was sequenced by Illumina Novaseq 2000 platform, and the SSR, SNP and InDel loci were analyzed using MISA and GATK3 software in gill, kidney, and liver of G.eckloni, after total RNA extraction and cDNA library construction. The results showed that a total of 128 727 SSR were found in 486 221 Unigenes, with a frequency of 26.47% and an average of one SSR per 3.76 kb; There were six repeat types in G.eckloni SSR, among which mononucleotide and dinucleotide were dominant, accounting for 46.53% and 42.45% of the total number of SSR loci, respectively. The total number of repeat motif types was 77, among which the frequency of the two motifs, A/T and AC/GT, were the most frequent, and they were the dominant repeat motifs in the SSRs of G.eckloni; Among all the repeats, the number of repeats between 5 and 15 was the largest, accounting for 87.52% of all SSR loci. In addition, 399 080 SNP loci were obtained by GATK3 software, and the transitions types were more than the transversion types, accounting for 56.29% and 43.71% of the total SNPs, respectively. The distribution frequency of A/G was slightly higher than C/T in the transition type, while the frequency of A/T was the highest and that of C/G was the lowest in the transversion type. The analysis showed that a total of 254 065 InDel loci were identified from the transcriptome of G.eckloni, with an average of one InDel locus per 1 903 bp. The largest number of unigenes was found in both SNP and InDel loci, and the unigenes containing one locus of SNP and InDel were the largest. The SSR, SNP and InDel loci were shown to be abundant in the transcriptome of G.eckloni, and the findings will be of great value for the identification of germplasm resources, population genetics and conservation management of the G.eckloni in the future.
  • Spatial and temporal distribution of chlorophyll a concentration and eutrophication evaluation in the middle reaches of Huaihe River
    HE Licong, WANG Dongwei, ZHANG Minying, ZHOU Yanfeng
    Journal of Dalian Ocean University. 2024, 39(1): 114-123. https://doi.org/10.16535/j.cnki.dlhyxb.2023-140
    Abstract (1244) PDF (468) HTML (0)   Knowledge map   Save
    In order to explore the spatial and temporal distribution characteristics and influencing factors of chlorophyll a (Chl-a) concentration and eutrophication in the middle reaches (from mouth of the Honghe River to the exit of Hongze Lake) of the Huaihe River, water quality was investigated in 28 sampling sections in the middle reaches of the Huaihe River in June 2019, September 2019 and February 2020, and the relationship between the spatial and temporal distribution of Chl-a and environmental factors were analyzed by principal component analysis and multiple linear stepwise regression analysis. The results showed that there was obvious spatial and temporal distribution characteristics of concentration of Chl-a in the middle reaches of the Huaihe River, with the annual mean value of (20.12±7.25)μg/L, with the variation range from 2.97 μg/L to 80.61 μg/L. The descending order of the spatial variation was expressed as Linhuaigang Sluice >from Linhuaigang Sluice to Bengbu Sluice >under Bengbu Sluice. Principal component analysis showed that Chl-a concentrations on Linhuaigang Sluice were positively correlated with transparency and dissolved oxygen level (P<0.05), but negatively correlated with nitrous nitrogen (P<0.05), and Chl-a concentrations from Linhuaigang Sluice to Bengbu sluice were significantly positively correlated with dissolved oxygen concentration and pH value (P<0.05), and Chl-a concentrations under Bengbu Sluice were positively correlated with permanganate index and total phosphorus (P<0.05). The multiple linear stepwise regression analysis revealed that pH, total phosphorus and total nitrogen were the main environmental factors affecting the concentration of Chl-a in the middle reaches of Huaihe River, pH being the passive factor for the change in Chl-a concentrations. There were obvious differences in the correlation between total nitrogen and concentration in different hydrological periods, and total phosphorus concentration was the limiting nutritional factors of phytoplankton in the middle reaches of Huaihe River. The water in the middle reaches of the Huaihe River was dominated by mild eutrophication, and the temporal and spatial variation characteristics of the comprehensive trophic status index (TLI) were similar to the changes in Chl-a concentration. The Linhuaigang Sluice and the confluence of the main stream of the Huaihe River with the Yinghe River and the Wuhe River were the main mutation points of water quality change. It was found that the total nitrogen concentration mainly exceeded the standard in the middle reaches of Huaihe River, and the changes in the hydrological situation of the river caused by dams, tributary inflows and non-point source pollution were the main influencing factors causing the change in the TLI.
  • Isolation, identification and biological characteristics of Bacillus licheniformis from the intestine of Pacific white leg shrimp (Litopenaeus vannamei)
    XU Zhenquan, HAN Guowei, REN Jing, ZHANG Zixuan, SUN Jingfeng, HAN Zhuoran
    Journal of Dalian Ocean University. 2024, 39(1): 74-82. https://doi.org/10.16535/j.cnki.dlhyxb.2023-137
    Abstract (1232) PDF (527) HTML (1)   Knowledge map   Save
    In order to screen strains with potential prebiotic effects on Pacific white leg shrimp (Litopenaeus vannamei), a strain (RHVJ) with high temperature (80 ℃) tolerance was isolated from the intestine of healthy Pacific white leg shrimp with body weight of (3.1±0.4)g, and identified by morphological observations, physiological and biochemical determination, and gene sequence alignment. The strain RHVJ was detected for pathogen antagonism, safety, tolerance analysis, and growth characteristics. The results showed that RHVJ was a gram-positive Bacillus, and tentatively identified as a Bacillus based on physiological and biochemical characteristics. The 16S rDNA sequence of RHVJ was found to be completely matched with Bacillus licheniformis strains MH305331.1 and NR074923.1, and its gyrB sequence also showed 100% consistency with CP038186.1 and CP023729.1. The strain RHVJ was identified as Bacillus licheniformis, inhibited the growth of Vibrio parahaemolyticus and Aeromonas veronii, and not pathogenic to Pacific white leg shrimp based on physiological and biochemical identification results. When cultured in environments with bile salt concentrations ranging from 0 to 1.2 g/L and pH levels between 3 and 11, and subjected to water bath treatments at temperatures from 37 to 90 ℃ for either 5 or 15 minutes, the RHVJ strain demonstrated sustained proliferation. It exhibited optimal growth under conditions of 27 ℃, pH 7, and 20 salinity. The B.licheniformis RHVJ from the intestine of Pacific white leg shrimp had good environmental adaptability and safety, as well as some ability to antagonize pathogenic bacteria, and were used as a candidate strain for the development of probiotics. The findings laid the foundation for its application in prawn culture.
  • Effects of air exposure and recovery on antioxidant capacity, apoptosis and immune related gene expression in coelomocytes of sea urchin (Strongylocentrotus intermedius)
    LIN Weigang, SUN Qi, HAI Hangyu, LIU Yating, ZHAO Peng, CHANG Yaqing, MA Deyou
    Journal of Dalian Ocean University. 2024, 39(1): 66-73. https://doi.org/10.16535/j.cnki.dlhyxb.2023-118
    Abstract (1199) PDF (537) HTML (0)   Knowledge map   Save
    To evaluate the effect of air exposure transportation on the survival of sea urchin (Strongylocentrotus intermedius), the total superoxide dismutase (T-SOD) activity, malondialdehyde (MDA) content and total antioxidant capacity (T-AOC) were determined during 12, 24 and 36 h air exposure stress and subsequent 12 h recovery, and apoptosis was detected by flow cytometry, and the expression levels of lysozyme gene LYZ, TLR1, Caspase-3 and Caspase-9 in coelomocytes were investigated using real-time quantitative PCR. The main results showed that the T-SOD activity, MDA content, and T-AOC level generally increased first and then decreased during exposure to air, with the maximum values observed at 12 h air exposure stress and no significant differences between control and 12 recovery (P>0.05). Air exposure had significant effects on the expression of immune related genes LYZ and TLR1, reaching the maximum values at 24 and 36 h of air exposure, which were significantly higher than those in other stress groups (P<0.05). Their expression levels after 12 h recovery following exposure times 36 h were also significantly different from those in controls (P<0.05). It was identified that the change trend of apoptosis rates was similar to that of the T-AOC levels, reaching the maximum value at 12 h air exposure. However, the expression levels of Caspase-3 and Caspase-9 genes presented significant differences between control and time intervals (P<0.05), with the maximum values observed at 24 h and 36 h of air exposure, respectively, suggesting response of the two important apoptosis-related Caspases had time cumulative effect. These findings indicated that sea urchins S.intermedius have certain ability on air exposure tolerance, using antioxidant enzyme system to conserve the dynamic balance of reactive oxygen species (ROS). Innate immune molecules such as lysozyme and TLR1, as well as Caspase dependent apoptosis, play important roles in maintaining homeostasis in response to air exposure stress.
  • An information extraction method from offshore aquaculture area based on spatial transformation and shuffle attention mechanism
    WU Tongren, ZHANG Xian, LIU Pei, WEN Tingting , ZOU Zhenxue
    Journal of Dalian Ocean University. 2024, 39(2): 327-336. https://doi.org/10.16535/j.cnki.dlhyxb.2023-230
    Abstract (760) PDF (275) HTML (0)   Knowledge map   Save
    In order to solve the problem of low accuracy in extracting aquaculture areas using remote sensing technology due to complex background of onshore aquaculture and offshore cage culture areas and to easily disturbed by factors including houses, vegetation, seawater, and ships, a complex deep learning method that combines shuffle attention mechanisms and spatial transformation network was proposed, and tested in Bamen bay in Wenchang city and Potou Port in Wanning City. With the help of GF-2 high resolution remotely sensed data, the prior knowledge of aquaculture targets was constructed using spectral and texture features. Then, based on the U-Net model, the spatial transformation network (STN) and the shuffle attention (SA) mechanism are combined to enhance the spatial characteristics of the aquaculture area and to reduce the interference of complex backgrounds. The test results showed that the overall accuracy and mean intersection over union of SA-STN-Net model were enhanced by 3.3% and 5.7% compared with the preliminary U-Net model, respectively. Swin-Transformer, Dc-Swin, and F1 score of SA-STN-Net model were found to be increased by 6.7%, 4.2% and 7.2% in the score compared with the most state-of-art deep learn model such as A2fpn, respectively. The findings demonstrate that the proposed SA-STN-Net model is adapted to the complex environmental background of offshore aquaculture, effectively extracts offshore aquaculture targets, and can provide technical support for offshore planning and management departments.
  • Revelation of green development of aquaculture industry in China from foreign provision of aquaculture tailwater discharge: a review
    MA Xiaona, ZHAI Tangfang, WU Ziheng, LIU Zishuo, YANG Yuxiang, FENG Zhihua, LIU Ying
    Journal of Dalian Ocean University. 2024, 39(2): 337-348. https://doi.org/10.16535/j.cnki.dlhyxb.2023-159
    Abstract (685) PDF (400) HTML (0)   Knowledge map   Save
    The provision of aquaculture tailwater discharge in some major foreign countries and international organizations at the national level (Global Aquaculture Alliance,United States, European Union, Norway, France, Japan, Australia and World Bank)are summarized, and the current status of aquaculture wastewater discharge standards in China is examined. The requirements for wastewater discharge in aquaculture are analyzed and compared between China and other countries. It is found that foreign countries place more emphasis on process management including BMP management and permit systems, focusing on reducing pollutant emissions at the source. In terms of pollution control modes, foreign countries often adopt a combination of concentration control and total load control, while domestic approaches tend to focus on concentration control alone. In terms of pollution control parameters, in addition to the five main pollutants controlled in China (suspended solids, pH value, COD, nitrogen, and phosphorus nutrients), foreign countries also pay more attention to pollutants such as dissolved oxygen, coliform bacteria, and oil substances. There are also differences in pollutant emission concentration limits between domestic and foreign countries: the primary discharge standard is slightly higher than the standards of most foreign countries, while the secondary standard is lower than international standards. Furthermore, present paper offers insights and recommendations for the development of domestic standards for aquaculture wastewater discharge from three aspects: strengthening source control, improving process monitoring, and innovating end-of-pipe treatment, aiming to provide scientific reference for researchers and management departments and to promote the healthy and sustainable development of aquaculture industry in China.
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Editor-in-Chief: SONG Linsheng
Deputy Editor-in-Chief:
ZHANG Guochen　LI Zhijun
LIU Ying　HAO Ladi
Sponsor: Dalian Ocean University
Supervisor: Education Department of Liaoning Province
Address: No. 52,Heishijiao street, Shahekou District, Dalian, Liaoning Province, China
Postal code: 116023
Tel: 0411-84762672
E-mail：xuebao@dlou.edu.cn
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