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  • Spatio-temporal ecological niche analysis of the dominant fishes in northeast Hangzhou Bay
    ZHOU Xuan, HONG Bo, ZHANG Yuping
    Journal of Dalian Ocean University. 2023, 38(5): 848-856. https://doi.org/10.16535/j.cnki.dlhyxb.2023-029
    Abstract (2769) PDF (1104) HTML (3)   Knowledge map   Save
    In order to probe the ecological niche characteristics of dominant fish species in the northeast Hangzhou Bay (30°00′-31°30′N,121°00′-122°24′E), a fixed net survey of fishing resources was monthly conducted from May to October 2020. The species composition, dominant species and ecological niche of fishery resources were analyzed by relative importance index, ecological niche breadth, ecological niche overlap index, and hierarchical clustering method. The results showed that there were 12 dominant species in three seasons, with dominant tapertail anchovy (Coilia mystus) and striped puffer (Takifugu xanthopterus) in all three seasons. The 12 dominant species had temporal niche breadth values from 0.10 to 1.01, with the maximal temporal niche breadth (1.01) in the tapertail anchovy and the minimal in Pampus argenteus. The 12 dominant species had spatial niche breadth values from 0.15 to 1.67, with the maximum in the tapertail anchovy and the minimal in Trypauchen vagina. The spatio-temporal niche breadth values of the 12 dominant species were found from 0.02 to 1.60, with the maximum in the tapertail anchovy and the minimal in P.argenteus. The spatial niche overlap of dominant fish species was high in the northeast of Hangzhou Bay, with 68.18% having overlapping significance, and 34.85% having significant overlapping significance. The ecological niche breadth of dominant fish species was found to be significant seasonal variation in the northeast of Hangzhou Bay, with the similar degree of spatial utilization, and difference in the utilization over time. Therefore, the study of spatio-temporal ecological niches of dominant species can not only further enrich the basic data of fishing resources in the northeast of Hangzhou Bay, but also provide scientific basis for the conservation and rational utilization of fishing resources in the northeast Hangzhou Bay.
  • Research progress on occurrence characteristics and toxic mechanism of typical PFAS in aquaculture water environment and aquatic products: a review
    WANG Chun, LI Guanyi, SUN Yingxue, YUAN Zixi, LI Ruixuan, WANG Mengyan, CHENG Bo
    Journal of Dalian Ocean University. 2023, 38(5): 893-901. https://doi.org/10.16535/j.cnki.dlhyxb.2023-037
    Abstract (2693) PDF (1067) HTML (0)   Knowledge map   Save
    Fish is one of the most actively traded products worldwide, and the quality of fish products is critical to economic development. Available studies have shown that dietary intake of fish is the main exposure pathway of per- and polyfluoroalkyl substances (PFAS) to humans via aquatic products. PFAS in aquaculture environment and aquatic products pose a direct threat to aquatic product quality and human health that cannot be ignored. In this paper, the state, bioenrichment effect and physiological toxicity of typical PFAS in aquaculture water and aquatic products are reviewed, the possible mechanisms of their effects on aquaculture organisms are explored, and functional probiotic strains to alleviate the toxic effects of PFAS are screened on aquaculture fish and their intrinsic mechanisms of action based on the demand for healthy aquaculture and green and safe aquatic products supply, and the problems in the current research are addressed. The risk of PFAS pollutants is objectively evaluated in aquaculture, the mechanism of functional strains to mitigate the toxicity of PFAS pollutants to cultured organisms, and the research and development of green and effective PFAS pollutant prevention and control technologies in aquaculture are proposed as the future key research directions, with a view to providing useful references to the scientific prevention and control of PFAS pollutants in aquaculture.
  • Optimization and quality analysis of mixed bacterial fermentation in sea bass
    NIE Shi, WU Yanyan, ZHAO Yongqiang, WANG Yueqi, LI Laihao
    Journal of Dalian Ocean University. 2023, 38(5): 885-892. https://doi.org/10.16535/j.cnki.dlhyxb.2023-021
    Abstract (2638) PDF (1092) HTML (2)   Knowledge map   Save
    In order to improve the flavor and texture of fermented sea bass, Lactobacillus plantarum and Pediococcus pentosaceus were used as additional composite strain fermenters, and sensory composite scores were used as evaluation indices to optimize the process conditions of mixed-bacteria fermentation of sea bass by using a single-factor test with the response surface method, and the effects of the inoculated fermentation on the quality of sea bass were further explored. The results showed that the optimal fermentation for sea bass were under conditions of 2∶1 volume ratio of P.pentosaceus to L.plantarum, 1.0% inoculum, 30 h fermentation and 3% fermented salt addition amount. Under this process condition, the a* value of inoculated fermented sea bass was increased from -1.89 to -0.94, b* decreased from 1.71 to 1.48, and improved color of fermented sea bass with natural fermented sea bass. The fermented sea bass had hardness increase from 40.17 g to 223.33 g, chewiness from 0.44 mJ to 3.29 mJ and gelatinousness from 33.27 g to 219.30 g, with significantly improved texture. The total acid mass fraction and amino nitrogen mass fraction were increased by 23.13% and 40.07% in the fermented sea bass with inoculated bacteria, respectively. Overall, the mixed bacterial fermentation of sea bass was beneficial to improve the quality and taste of sea bass.
  • Correlation analysis between metabolic characteristics and quality indices in muscle of Pacific white shrimp (Litopenaeus vannamei) during superchilling storage based on LC-MS non-targeted metabolomics
    YANG Kaiying, PAN Chuang, HAO Shuxian, CHEN Shengjun, LIU Shucheng, YANG Xianqing
    Journal of Dalian Ocean University. 2023, 38(5): 874-884. https://doi.org/10.16535/j.cnki.dlhyxb.2023-014
    Abstract (2634) PDF (1061) HTML (1)   Knowledge map   Save
    To investigate the mechanism of quality deterioration of superchilled shrimp, metabolites change of Pacific white shrimp (Litopenaeus vannamei) during superchilling storage at -3 ℃ (0, 10, 20, 30 d) were investigated through liquid chromatography-mass spectrometry non targeted metabolomics. The key metabolites were screened by the correlation analysis between the potential biomarkers and the quality indices (including water holding capability, texture, pH, myofibrillar protein content, surface hydrophobicity and turbidity). The results showed that significant differences were observed in the whole metabolic composition of shrimp muscle during superchilling storage. According to the OPLS-DA model, 79 significant different metabolites were screened from the shrimp muscle at different superchilling storage times. These different metabolites notably altered with the extension of time. The main metabolic pathways involved were biosynthesis of amino acids, biosynthesis of alkaloids derived from histidine and purine, lysine biosynthesis, citrate cycle (TCA cycle) and biosynthesis of alkaloids derived from ornithine, lysine and nicotinic acid. The quality indices showed that water holding capability, hardness, springiness and myofibrillar protein content gradually decreased during storage, while pH, surface hydrophobicity and turbidity gradually increased. The pathway analysis combined with correlation analysis revealed that L-lysine, L-aspartic acid, citric acid and isocitric acid were used as the key metabolites related to the metabolites for the quality changes of shrimp muscle during superchilling storage. This study revealed the metabolic characteristics of superchilled shrimp muscle at the molecular level, providing a theoretical basis for quickly and accurately reflecting the actual-time quality of shrimp muscle.
  • Numerical simulation of the effect of cultured fish on the hydrodynamics in a aquaculture tank
    SHI Xianying, LI Meng, HUANG Zhengzheng, FENG Dejun, REN Xiaozhong, LIU Hangfei, SUN Wei
    Journal of Dalian Ocean University. 2023, 38(5): 839-847. https://doi.org/10.16535/j.cnki.dlhyxb.2022-340
    Abstract (2613) PDF (1105) HTML (1)   Knowledge map   Save
    In order to investigate influence of fish on flow field characteristics of the aquaculture tank, the model of rounded square aquaculture tank with single inlet and cultured fish was established based on computational fluid dynamics (CFD), and the multiple reference frame method (MRF) was adopted to simulate the movement of fish under a fixed track. Influence of culture density, individual volume size and spatial distribution of fish in tanks on fluid flow characteristics in the aquaculture tanks was analyzed. Results revealed that the increase in culture density causes a great drop in average flow velocity in the aquaculture tanks under the same individual volume size and spatial distribution conditions. The upstream movement of fish makes high resistance to the flow and much greater drop in average flow velocity at the fixed culture density, and large school of fish (while the individual volume size is small). The maximal average flow velocity drops and turbulence intensity rise in the aquaculture tank caused by the school are observed at the fixed culture density and individual volume size, and distribution of the school of fish in the middle layer of the water. There were the least influences of the school on average flow velocity and turbulence intensity at the fixed culture density and individual volume size, and distribution of the school of fish in the lower layer of the water. Therefore, inlet current velocity of the aquaculture tank was properly adjusted, with culture density, individual volume size and spatial distribution to maintain flow field condition suitable for fish survival and growth.
  • Research progress on the factors influencing mariculture wastewater treatment by constructed wetland:a review
    ZHANG Cuiya, CHEN Feng, GUO Xianyong, LIU Jiaxuan, ZHANG Kun
    Journal of Dalian Ocean University. 2023, 38(5): 902. https://doi.org/10.16535/j.cnki.dlhyxb.2023-040
    Abstract (2593) PDF (1121) HTML (1)   Knowledge map   Save
    The rapidly developing marculture industry generates a large amount of aquaculture tail water, which can threaten the ecological environment of local offshore waters. Constructed wetlands as typical wastewater treatment process are advantage features including low energy consumption, low investment, and resistance to impact loads, showing good application prospects in purifying seawater aquaculture tail water. This article reviews the effects of factors such as plants, substrates, denitrifying microorganisms, operating parameters, and salinity on the performance of constructed wetlands in purifying mariculture tail water. The problems in current research on purifying seawater aquaculture tail water by constructed wetlands are analyzed, focusing on future research, including selecting suitable substrates and salinity tolerant plants, optimizing hydraulic operating parameters, and the impact of complex environments on the ability of seawater constructed wetlands to purify mariculture tail water is discussed. The technologies that can enhance the purification capacity of constructed wetlands, and search for alternative high quality carbon sources are suggested, in order to provide reference for further research on the mechanism and application of constructed wetlands in purifying mariculture tail water.
  • Effects of chelicerae autotomy and regeneration on feeding and aggressive behaviors of swimming crab (Portunus trituberculatus)
    TAO Dandan, LIU Lei, FU Yuanyuan, WANG Sixiang, HUANG Xinlian, ZHAI Wei, XU Yuankai, SONG Weiwei, WANG Chunlin
    Journal of Dalian Ocean University. 2023, 38(5): 795-803. https://doi.org/10.16535/j.cnki.dlhyxb.2023-003
    Abstract (2575) PDF (1175) HTML (0)   Knowledge map   Save
    In order to study the effects of chelicerae autotomy and regeneration on the feeding and aggressive behaviour of swimming crab (Portunus trituberculatus), the method of high-temperature stress chelicerae autotomy was established in swimming crab with body weight of (18.34±2.56)g (phase C in molt). The body weight, total carapace length, total carapace width, body height, feeding rate, weight growth rate, morphological indicators, and growth rate were measured in swimming crab (no cheliped autotomy, control group), one cheliped autotomy group and two chelipeds autotomy group after chelicerae autotomy and regeneration. The changes in feeding selectivity, feeding ability and aggressive behaviour were observed in the swimming crab before and after autotomy and regeneration by EthoVision XT behavioural tracking system. The results showed that the swimming crab had slight decrease in growth rate of body weight in the cheliped autotomy groups compared to the control group (P>0.05), and significant decrease in the growth rate of total carapace width, total carapace length and body height in the two chelipeds autotomy group (P<0.05). There was slight decrease in feeding rate of clam meat and trash fish in the autotomy groups compared with that in the control group, with similar feeding rate among the regeneration groups, without any significantly different (P>0.05). Both two cheliped autotomy groups and two cheliped regeneration groups was not able to open Musculus senhousei, with significant difference from the control group (P<0.05). The swimming crab with amputated and regenerated chelicerae changed the feeding preference significantly compared with the swimming crab in the control group (P<0.05). The fight delay time was shown to be decreased, in steady of the fight duration, fight moving speed, fight moving distance and fight intensity tended to be increased in cheliped autotomy group, as the number of chelicerae autotomy increased, with the maximal significant difference in fight duration and fight intensity in cheliped autotomy group compared with that in the control group (P<0.05). It was found that cheliped autotomy led to reduce the growth rate of body weight and morphological indicators in the juvenile swimming crab. The food ingestion rate on clam meat and trash fish and aggressive ability were decreased after cheliped autotomy in the juvenile swimming crab, without effect of the regeneration of the chelicerae on the feeding rate of clam meat and trash fish.
  • Effects of light color, light intensity and photoperiod on growth and feeding of juvenile turbot (Scophthalmus maximus)
    HAN Jian, WANG Maolin, CAO Shengnan, GU Zhizhi, SUN Xu, WANG Wei
    Journal of Dalian Ocean University. 2023, 38(5): 787-794. https://doi.org/10.16535/j.cnki.dlhyxb.2023-018
    Abstract (2572) PDF (1188) HTML (4)   Knowledge map   Save
    In order to evaluate effects of light environment (light color, light intensity and photoperiod) on growth and feeding of juvenile turbot (Scophthalmus maximus) during culture, juvenile turbot with initial body weight of (3.17±0.07)g was reared in a flowing water tank of 85 cm×75 cm×60 cm under cold white, red, blue, green, and warm white LED light, and light intensity of 600, 300, 100, 25 lx and the dark control and photoperiod of 24L∶0D, 16L∶8D, 12L∶12D, 8L∶16D and the dark control at cold white light and water temperature of(18.3±0.5)℃ for 65 days. At the end of the experiment, the survival rate, specific growth rate, feed conversion ratio and the levels of GH, IGF-1, and NPY were comprehensively analyzed. The results showed that there was higher mortality of juvenile turbot in the red light source group, without significant effect of the light color, light intensity and photoperiod on the survival rate (P>0.05). The juvenile turbot had significantly lower growth and feeding performances in red light source group than those in cold white and green light source groups (P<0.05). The growth and feeding performances of juvenile turbot were shown to be significantly higher in 300 and 100 lx groups than those in 600 lx group (P<0.05). The juvenile turbot had significantly lower growth and feeding performances in continuous light group (24L∶0D) than those in 12L∶12D, 8∶16D and dark control groups (P<0.05). The findings suggest that the use of red light be avoided during the culture of juvenile turbot. The low light intensity (25-300 lx) is suitable for the growth and feeding of juvenile turbot, while the high light intensity inhibits the growth and feeding. The short photoperiod (0-12 h light) appears to be more conductive to the growth and feeding of juvenile turbot than long photoperiod.
  • Optimization of enzymatic hydrolysis process and sensory characterization for rag worm (Perinereis aibuhitensis) umami hydrolysate
    LIU Tianhong, JI Lei, YU Xiaoqing, WANG Qi, WANG Ying, JIANG Xiaodong, LI Hongyan, SUN Yuanqin, LI Xiao
    Journal of Dalian Ocean University. 2023, 38(5): 857-865. https://doi.org/10.16535/j.cnki.dlhyxb.2023-013
    Abstract (2570) PDF (1006) HTML (0)   Knowledge map   Save
    In order to improve the utilization scope and economic value of rag worm (Perinereis aibuhitensis) effectively, the optimal complex enzymatic hydrolysis process of the umami polypeptide and the flavor characterization of the product from the rag worm with body weight of 300-400 individuals/kg were investigated by using response surface methodology and various characterization methods. The hydrolysate umami peptides powder was prepared and lyophilized by ceramic membrane and ultrafiltration membrane. The results showed that the flavor protease and animal protease were used as the best enzymes for preparing the flavoring peptide. The optimum technological conditions were obtained by response surface methodology: flavor protease and animal protease complex (m∶m=2∶1), material-liquid ratio of 1∶1 (g∶mL), pH 6.5, enzyme concentration of 600 U/g, and enzymatic hydrolysis in 4 h. There was hydrolysate DH of 32.64% and the sensory score of 8.73. The electronic tongue detection indicated that the peptide had obvious umami taste. The free amino acid analysis revealed that the umami amino acids accounted for 32.76% of the total free amino acids, and contained 13 kinds of functional amino acids, with the better taste and smell in the peptide than that in the traditional seasoning soy sauce powder. In conclusion, the hydrolyzed peptides from rag worm had obvious umami and aromatic odors, which could be used to develop functional seafood flavor substrates.
  • Isolation, purification and hypoglycemic activity of polysaccharides derived from brown seaweed (Eucheuma gelatinae)
    SHI Shuo, SUN Kangting, LI Jiwei, PAN Chuang, YANG Xianqing, ZHAO Yongqiang, CHEN Shengjun
    Journal of Dalian Ocean University. 2023, 38(5): 866-873. https://doi.org/10.16535/j.cnki.dlhyxb.2023-034
    Abstract (2537) PDF (1036) HTML (0)   Knowledge map   Save
    In order to characterize the structure of polysaccharide from brown seaweed (Eucheuma gelatinae) and probe the hypoglycemic activity of its crude polysaccharide (EGP) and purified components (EGP-1, EGP-2, EGP-3), the E.gelatinae polysaccharide was extracted by ultrasonic assisted enzymatic method, and purified by DEAE-52 anion column and derivated by 1-phenyl-3-methyl-5-pyrazolone (PMP). The monosaccharide composition of each component was determined by high performance liquid chromatography (HPLC). The results showed that EGP and EGP-1, EGP-2 and EGP-3 were all pyran-saccharides polysaccharides, mainly composed of five monosaccharides: mannose, glucose, galactose, xylose and arabinose. The protein content of EGP-1, EGP-2 and EGP-3 was significantly lower than that of polysaccharide EGP, and the content of uronic acid and sulfate of EGP- 2 and EGP-3 was significantly increased. The EGP and EGP-1 had atriple helix structure, while EGP-2 and EGP-3 had no triple helix structure. The determination of hypoglycemic activity in vitro revealed that four polysaccharides effectively inhibited the activity of α-amylase and α-glucosidase in a dose-dependent manner, with the best hypoglycemic effect in EGP-3. The finding indicated that the molecular mass of the three purified components were reduced and that had stronger hypoglycemic activity compared with EGP.
  • Comparison of habitat suitability of fiddler crab (Uca arcuata) based on habitat suitability index model and maximum entropy model
    ZHOU Xin, ZHANG Liyuan, HE Chenxiang, HU Chengye, WANG Jing, LI Yi, LI Xueli, SHUI Bonian
    Journal of Dalian Ocean University. 2023, 38(5): 819-827. https://doi.org/10.16535/j.cnki.dlhyxb.2023-010
    Abstract (2517) PDF (1075) HTML (1)   Knowledge map   Save
    For understanding of the habitat suitability and optimal analysis model of fiddler crab (Uca arcuata), key environment factors affecting changes in habitat suitability, and the predictive performance, scope and limitations of application of the two habitat suitability models including habitat suitability index (HSI) model and the maximum entropy (MaxEnt) model were compared with a view to species classification of mangrove ecosystems based on the survey on mangrove macrobenthos and several environmental factors in Yanpu Bay (27.20°N, 120.45°E) Wenzhou City, Zhejiang Province during July (summer), October (autumn) and December (winter) of 2020 to provide theoretical support for applied research on biodiversity conservation and scientific basis for ecological environment governance and decision-making. HSI model analysis showed that the descending order of the habitat suitability of the sampling stations was expressed as nearshore>middle>offshore section, with the southeast>the northwest in the spatial distribution, and significantly different habitat suitability in the three seasons (P<0.05), generally as summer>autumn>winter. The analysis of the maximum entropy (MaxEnt) model revealed that the descending order of habitat suitability of the fiddler crab in each sampling site as nearshore>middle section>offshore section, the southeast>the northwest, and autumn>summer>winter in the seasonal distribution. The HSI model was shown to be more suitable for the investigation of the suitable area of the fiddler crab than the MaxEnt model being; temperature, bottom, geology and tide were the environmental factors affecting the distribution; nitrate, nitrite and salinity were the key physical and chemical factors affecting the distribution of the fiddler crab, which have a strong driving force for the distribution pattern and influence the choice of suitable habitat.
  • Rethinking and optimization of releasing stock enhancement for marine fishery resources: a review
    SHUI Bonian
    Journal of Dalian Ocean University. 2023, 38(5): 737-743. https://doi.org/10.16535/j.cnki.dlhyxb.2023-170
    Abstract (2501) PDF (1269) HTML (3)   Knowledge map   Save
    Releasing stock enhancement could increase the amount of marine fishery resources, improve the marine environment, and repair the marine ecology by repairing the marine food web. There is insufficient research on release of marine ecology and fishery resources. The strategy is not specific. Various critical aspects such as location and time arrangement, supervision and management coordination, and evaluation of multiplication effects need to be optimized. The suggestions for improvement and optimization are provided. The variety, quantity, density and ratio of the release should be selected scientifically. The spatio-temporal arrangement of the release should be fully demonstrated in advance. The supervision and management of the release should be implemented. A coordination and linkage mechanism should be built between the administrative departments of the sea area and the administrative region. The monitoring and evaluation of the comprehensive effects of the multiplication and release should be emphasised. The retrospective evaluation and continuous improvement system should be established. These measures would facilitate the sustainable growth of China’s Marine fishery resources.
  • Effects of sediment type and shell length on burrowing behavior and feeding rate of razor clam (Sinonovacula constricta)
    ZHANG Shuyuan, WANG Xinxing, LIU Qi, LI Yifeng, SHEN Heding, NIU Donghong
    Journal of Dalian Ocean University. 2023, 38(5): 804-811. https://doi.org/10.16535/j.cnki.dlhyxb.2022-361
    Abstract (2495) PDF (1061) HTML (0)   Knowledge map   Save
    In order to investigate the sediment selection and feeding differences of razor clam (Sinonovacula constricta) after burrowinging, different sizes of razor clam with shell lengths of 2.5, 3.0, and 3.5 cm were used as experimental objects to study the effects of different sediment types (total mud, 1/3 sand, 2/3 sand, total sand) and sediment thickness (6, 12, 18, 24, and 30 cm) on burrowing behavior and feeding rate. The results showed that the size and sediment type had a very significant interactive effect on the burrowing rate and time (P<0.01), with 100% of burrowing rate only within 24 hours in total mud sediment. The burrowing behavior of razor clam was obviously blocked at the sediment containing over 30% of sand, with significant difference in the half shell vertical time (TE50) between different sizes (P<0.05). There was no significant interaction of clam shell sizes and sediment thickness on the burrowing rate, burrowing time and feeding rate (P>0.05), with significant positive correlation between individual size and burrowing depth and feeding rate (P<0.05). The razor clam with a shell length of 3.5 cm had burrowing depth at about 2/3 of the sediment thickness, and as high 2.12 times feeding rate as that the individuals in a thickness of 6 cm did, under a sediment thickness of 6 cm, with the maximal feeding rate of razor clam with a shell length of 2.5 cm. In conclusion, the suitable sediment for burrowing of razor clam is muddy, with strong burrowing ability in small sizes. The thicker the sediment is, the more conducive to feeding after burrowing is.
  • Genetic diversity and genetic structure of selected generations of Chinese pond turtle (Mauremys reevesii) based on microsatellite DNA
    XU Haoyang, YANG Xueying, NI Wei, LIU Fang, CHEN Haigang, ZHU Xinping, LIU Xiaoli
    Journal of Dalian Ocean University. 2023, 38(5): 812-818. https://doi.org/10.16535/j.cnki.dlhyxb.2022-341
    Abstract (2492) PDF (1048) HTML (0)   Knowledge map   Save
    In order to probe selective breeding effect of Chinese pond turtle (Mauremys reevesii), the genetic diversity and genetic structure were analyzed in five selective breeding generations of the wild and protospecies of Chinese pond turtle, including basic group F0 generation, and F1-F4 generation groups by polymorphic microsatellite (SSR) markers. The results showed that 103 alleles were detected in the 12 selected microsatellite loci, with the average allele number (Ha) of 8.58. The expected heterozygosity (He) was varied from 0.173 to 0.919, with mean of 0.581. The observed heterozygosity (Ho) was found to be 0.054-0.862, with an average of 0.479. Polymorphic information content (PIC) was changed from 0.165 to 0.914, with average of 0.531. There were 11 moderately or highly polymorphic loci in the 12 microsatellite loci, indicating that the microsatellite loci selected in this study can be used as a good evaluation tool for the analysis of genetic diversity and genetic structure of selective breeding generations of Chinese pond turtle. The (Ho) of the five selective breeding generations was 0.491, 0.494, 0.497, 0.458 and 0.453, respectively. The genetic differentiation coefficient (Fst) and AMOVA analysis revealed that the (Fst) values between the five breeding generations were 0.004-0.012, less than 0.05. The findings indicated that the genetic diversity of the selective breeding generation of Chinese pond turtle was decreased, with less degree of genetic differentiation between five generations. Therefore, the selective breeding population of the Chinese pond turtle still has the potential further breeding.
  • Stock assessment for albacore tuna (Thunnus alalunga) in the Indian Ocean based on JABBA-Select model under different time series of catch and fishing vessel effects
    YANG Shiyu, FENG Ji, ZHU Jiangfeng
    Journal of Dalian Ocean University. 2023, 38(5): 828-838. https://doi.org/10.16535/j.cnki.dlhyxb.2022-357
    Abstract (2485) PDF (1049) HTML (0)   Knowledge map   Save
    In order to understand population dynamics and resource exploitation status of albacore tuna (Thunnus alalunga) in the Indian Ocean and to promote the sustainable exploitation of the fishery resources, the JABBA-Select model combining the biological parameters of the stock and fishery selectivity was used to assess albacore tuna, focusing on the impact of different time series of catch and with or without considering the fishing vessel effects in standardized CPUE on the stock assessment. The results showed that the model with short time series of catch from 1979 to 2020 and longline CPUE with vessel effect fitted better than the model with time series from 1950 to 2020, resulting in the estimated stock neither to be overfished (BSB/BSB,MSY>1) nor subject to overfishing (F/FMSY<1) in 2020. The sensitivity analysis indicated that the stock assessment results were robust to steepness (h), but sensitive to natural mortality (M). The finding showed that the stock assessment results varied with different time series of catch data, and the standardized CPUE considering the fishing vessel effect better reflected the dynamics of stock,with decrease in the uncertainty of assessment.
  • Transcriptomics analysis of echiuran worm (Urechis unicinctus) in response to BPA stress
    XU Xinghong, DING Ziyuan, ZHANG Xinyu, LIU Shun, QI Lu, WANG Sijie, ZHU Daqian
    Journal of Dalian Ocean University. 2023, 38(5): 744-752. https://doi.org/10.16535/j.cnki.dlhyxb.2023-006
    Abstract (2468) PDF (1061) HTML (0)   Knowledge map   Save
    To explore the molecular mechanism of bisphenol A (BPA) toxicity effects on echiuran worm (Urechis unicinctus),echiuran worm with body weight of (17.3±1.5)g was exposed to 3 mg/L BPA (0.15% of anhydrous ethanol as co-solvent) and sea water (control group) and then the transcriptome sequencing was adopted for coelomocytes of the echiuran worm under an Illumina Hiseq 2500 platform. The results showed that 13.74 Gb of high-quality sequencing data were obtained with Q30≥93.02%, 108 262 transcripts and 30 882 Unigene were assembled, with average length of 1 380 bp and N50 of 2 549 bp. Eight data bases (NR, GO, COG, Swiss-Prot, KOG, KEGG, eggNOG4.5 and Pfam) were selected for the Unigene annotation, with 14 581 annotated Unigene, in which 7 242 Unigene were annotated to genes in KEGG database, further being classified into 284 metabolic pathways. Gene differential expression analysis indicated that 1 073 transcripts were differentially expressed in response to BPA stress, including 649 up-regulated genes and 424 down-regulated genes. GO functional classification showed that the differentially expressed genes were primarily involved in the biological process of catalytic activity, binding, antioxidant, transporter, signal transducer and electron carrier. The KEGG enrich analysis revealed that 163 genes were mapped into 151 pathways, and three most significantly enriched pathways were ribosome biogenesis in eukaryotes, glutathione metabolism, and metabolism of xenobiotics by cytochrome P450. The synthesis, immonology and detoxification metabolism of the coelomocytes elucidated the adverse effects of BPA on echiuran worm. The findings provide the reference data with the marine biotoxicity research of environmental endocrine disruptors(EEDs) and anti-stress mechanism of echiuran worm.
  • Effects of different aquatic plants on growth performance, physiological indices and muscle nutrients of red swamp crayfish (Procambarus clarkii)
    WU Leiming, HAN Guangming, QIN Baoli, ZHANG Jiahong, WANG Shouhong, KOU Xiangming, YUAN Qin, BI Jianhua, TANG Hejun
    Journal of Dalian Ocean University. 2023, 38(5): 779-786. https://doi.org/10.16535/j.cnki.dlhyxb.2023-044
    Abstract (2447) PDF (1098) HTML (0)   Knowledge map   Save
    In order to clarify influence mechanism of aquatic plant environment on growth and development of red swamp crayfish (Procambarus clarkii), juvenile red swamp crayfish with body weight of (3.54±0.73)g were reared in a 2.5 m length×2.0 m wide×1.2 m high canvas box with 0.3 m depth of soil at bottom for planting aquatic plants Hydrilla verticillata (group HM), Alternanthera philoxeroides (group AM)and bionic plastic aquatic plant (control group, BM) at coverage rate of 50% at initial density of 30 crayfish per box at water temperature of (23.51±2.92)℃ for 62 d. Breeding period, the culture boxes were aerated for oxygenation at night and on rainy days. The results showed that there was significantly higher dressing rate in the crayfish in group HM than that in the BM group (P<0.05). The crayfish had higher survival rate and total weight in groups HM and AM than those in the control group did, increased by 12.12%, 11.42% and 16.68%, 25.78%, respectively. The activities of trypsin and cellulose in hepatopancreas were shown to be significantly higher in groups HM and AM than those in group BM (P<0.05), and significantly lower activities of trypsin and cellulase in intestine in groups HM and AM than those in group BM (P<0.05), without significant difference in amino acid content among all groups (P<0.05). ∑(n-3) polyunsaturated fatty acid (PUFA)/∑(n-6)PUFA of muscle was significantly higher in HM and AM groups than that in group BM (P<0.05). The contents of EPA, DHA, ∑SFA and ∑PUFA were found to be significantly higher in the muscle in group HM than those in group BM (P<0.05). The findings indicate that the aquatic vegetation environment has a significant impact on the growth performance, physiological indicators, and muscle nutrient quality of red swamp crayfish during cultivation. Planting H.verticillata is more conducive to improving the muscle quality of crayfish.
  • Sequence characteristics, SNP locus and association with growth traits of insulin-induced gene 1 (INSIG1) in Yellow River carp (Cyprinus carpio haematoperus)
    WANG Xinhua, LU Chang, XU Wenyan, QI Zixin, XU Mengmeng
    Journal of Dalian Ocean University. 2023, 38(5): 763-771. https://doi.org/10.16535/j.cnki.dlhyxb.2023-001
    Abstract (2438) PDF (1070) HTML (0)   Knowledge map   Save
    In order to explore the function of insulin-induced gene 1 (INSIG1) in the growth and development process of Yellow River carp (Cyprinus carpio haematoperus), the sequence characteristics, expression patterns and SNP association with growth traits of INSIG1 in 26 all-sibling lineages of Yellow River carp (Cc-INSIG1) were analyzed based on the candidate gene approach. The results showed that the full-length DNA of Cc-INSIG1 gene was 4 853 bp, containing 5 exons and 4 introns, and the full-length cDNA of Cc-INSIG1 gene was 1 530 bp, including 756 bp of the coding sequence, encoding 251 amino acids. The amino acid sequence of Cc-INSIG1 showed high homology with INSIG1 of other species, and clustered with other fish species in Cyprinidae like horned golden-line barbel (Sinocyclocheilus rhinocerous), zebrafish (Danio rerio) and crucian carp (Carassius auratus). The Cc-INSIG1 protein had relative molecular mass of 27 674.25 and the theoretical isoelectric point (pI) of 8.09, and belonged to the stable hydrophobic protein, without signal peptide. The structure analysis revealed that there were 6 transmembrane structures and the tertiary structure mainly consisted of 6 alpha helices and random coils. Real-time PCR analysis showed that Cc-INSIG1 was ubiquitous expressed in liver, spleen, kidney, intestine, heart, gill, brain, muscle and skin, with extreme predominance in intestine and liver, and the minimum in gill. Ten single-nucleotide polymorphisms (SNP) were identified in DNA sequence of Cc-INSIG1, two, that is, g.1854T>C and g.1982A>T, were significantly associated with Fulton’s condition factor (K) in the populations of Yellow River carp (P<0.05), and without association with growth traits in other SNP. It was found that INSIG1 gene was involved in the growth and development of Yellow River carp, and its mutation sites g.1854T>C and g.1982A>T significantly influenced the Fulton’s condition factor of Yellow River carp. The findings provided available markers for gene (marker)-assisted selective breeding in Yellow River carp, which has great significance to the breeding of Yellow River carp with excellent economic traits.
  • Progress in research on vibriosis and biological control in animals in aquaculture: a review
    DENG Yiqin
    Journal of Dalian Ocean University. 2023, 38(4): 553-563. https://doi.org/10.16535/j.cnki.dlhyxb.2023-156
    Abstract (2437) PDF (1364) HTML (278)   Knowledge map   Save
    Vibriosis as one of the main bacterial diseases in aquaculture, is causing harm to fish, shrimp, crabs, and shellfish, and development of its control techniques is of great significance for promoting sustainable development of aquaculture. The control methods of vibriosis mainly include drug, immune, and biological control, which are respectively represented by antibiotics, vaccines, and probiotics. Basing on the relationship between species, biological control is the method of inhibiting another organism or class of organisms by using an organism or class of organisms or their derivatives. It can carry out broad-spectrum disease control throughout the entire breeding process with little effect on the environment and food safety, which is a promising control technology. Currently, the biological control methods of vibriosis in aquaculture primarily include probiotics, medicinal plants, and bacteriophages. Based on the introduction of the etiology, epidemiology, pathogenesis and diagnosis of vibriosis in aquatic animals, we review the research on biological control of vibriosis in aquaculture animals from the aspects of control types, control mechanisms and applications of control technology. In addition, the main direction of future research on biological control of vibriosis is proposed: while deeply exploring its mechanism and mode of action, ensure environmental friendliness, high quality and efficiency, and promote its commercial development, thus to provide scientific reference for biological control of vibriosis in aquaculture.
  • Complete mitochondrial genome sequencing and phylogeny analysis of goby (Taenioides cirratus)
    LIANG Yangyang, ZHANG Guoqing, CHEN Cheng, ZHAO Xiuxia, GAO Na, LI Jing, FANG Ting, YANG Kun, YIN Feng, GUO Wei, LU Wenxuan
    Journal of Dalian Ocean University. 2023, 38(5): 772-778. https://doi.org/10.16535/j.cnki.dlhyxb.2022-216
    Abstract (2404) PDF (1023) HTML (1)   Knowledge map   Save
    To clarify the mitochondrial genome characteristics and phylogenetic status of goby (Taenioides cirratus), the complete mitochondrial genomes were analyzed in 12 samples collected from the Nandu River Estuary, Pearl River Estuary, Taihu Lake, Chaohu Lake and Nansi Lake and download the mitochondrial genome sequences of closely related species for phylogenetic analysis by the second generation high throughput sequencing technology. Results showed that the length of individual mitochondrial genome was ranged from 16 641 to 16 978 bp, containing 13 protein coding genes (PCGs), 22 tRNA genes, 2 rRNA genes and the D-loop. The length of each coding gene sequence for every sample was relatively consistent, and the difference in length of the mitochondrial genome was mainly caused by the difference in D-loop length (975-1 314 bp). Based on the 13 PCG and 2 rRNA gene sequences, phylogenetic analysis combined the sequences in present study with published closely related mitogenomes showed that the goby was divided into 3 major clades. Samples from Taihu Lake, Chaohu Lake and Nansi Lake were clustered into one clade while samples from the Nandu River Estuary or the Pearl River Estuary were divided into two clades. Cladistic analysis depicted that T.cirratus was showed to form a paraphyletic group with Odontamblyopus rubicundus and Taenioides anguillaris. The uplift of the Qinghai-Tibet Plateau and the formation of the Asian monsoon that brought about changes in water system pattern in China were the likely causes for the formation of T.cirratus current phylogenetic status. The finding provides crucially important basis for the resource conservation and further taxonomic clarification of T.cirratus.
  • Advances in effects and regulatory mechanism of cortisol on process of sex differentiation in fish: a review
    GAO Rui, YAN Hongwei, LIU Ying, LIU Qi
    Journal of Dalian Ocean University. 2023, 38(4): 726. https://doi.org/10.16535/j.cnki.dlhyxb.2022-293
    Abstract (2329) PDF (1075) HTML (9)   Knowledge map   Save
    Sex determination and differentiation of fish has been increasingly concerned in the fields of developmental biology, reproductive physiology, and genetics and breeding in recent years. Unlike other vertebrates, sex determination and differentiation of fish are featured by high plasticity, and is influenced by several environmental factors such as temperature, density, and pH. Exploration of the molecular mechanism of sex determination and differentiation of fish is crucially important for sex control breeding, and conducive to improving aquaculture efficiency. Recently, is proved cortisol, the predominant glucocorticoid in fish, has an important role in the process of sex differentiation in fish. The effects of exogenous cortisol treatment on fish sex differentiation, the effects of environmental factors on the variation pattern of endogenous cortisol levels during fish sex differentiation and sex change, and the molecular mechanism of cortisol in regulating sex differentiation and sex change are summarized. Some suggestions for future research are proposed including understanding of the mechanism of cortisol-induced masculinization and the interaction of cortisol and epigenetic factors, aiming to provide theoretical reference for further exploring the functional and regulatory roles of cortisol.
  • Distribution of marine Synechococcus assemblage in Qiongdong upwelling in northwestern South China Sea
    HOU Qinghua, YE Yingyi
    Journal of Dalian Ocean University. 2023, 38(5): 753-762. https://doi.org/10.16535/j.cnki.dlhyxb.2023-011
    Abstract (2250) PDF (1032) HTML (0)   Knowledge map   Save
    In order to explore the distribution characteristics and coexistence relationship of marine Synechococcus assemblage on the precise spatial scale in the coastal upwelling area from 18°30′-20°30′N to 110°00′-111°30′E, the horizontal and vertical spatial distribution of ten clades of Synechococcus was investigated in the water of the Qiongdong upwelling area in the northwest of the South China Sea in summer by 16S-23S rDNA internal transcribed spacer (ITS) quantitative polymerase chain reaction (qPCR) technology. The results showed that the ten clades of Synechococcus were widely distributed in Qiongdong upwelling water, and presented obvious spatial niche partitioning in the horizontal and vertical directions. The dominant clades were Ⅱ, Ⅲ, Ⅹ and CRD1 (Costa Rica dome), and the maximal average abundance of all the ten Synechococcus was cladeⅡ in the Qiongdong upwelling water. Types Ⅱ, Ⅲ, Ⅳ and Ⅹ were highly abundant in the surface water and coexisted with each other. The isolines of clades Ⅱ, Ⅲ and Ⅳ abundances were significantly elevated to the near-shore subsurface water, with positively correlated with temperature and dissolved oxygen (DO)level, and negatively correlated with salinity, reflecting the influence of upwelling dynamic processes on their coexistence. There was the peak abundance of clades Ⅰ, Ⅷ and Ⅹ in the surface water of the coastal estuary, which was mainly affected by river runoff. The distribution of CRD1, CRD2, ⅩⅤ and ⅩⅥ types in the subsurface water of Qiongdong area were co-occured, without significant correlation relationship with temperature, DO and salinity on the whole. There were different ecological clades of Synechococcus in different niches. Temperature, salinity, DO, upwelling dynamic process and river flow affected the different niche partitioning of Synechococcus assemblage in the Qiongdong upwelling area. The findings provided theoretical foundation for further study on the function of marine Synechococcus assemblage.
  • Spatial and temporal characteristics of phytoplankton functional groups and relationship with water environment factors in Hailaer River
    LIU Zixuan, WANG Yingying, ZHAO Chang, CHANG Changran, DOU Huashan, CHEN Xingyao, TAO Yulong, MA Chengxue
    Journal of Dalian Ocean University. 2023, 38(4): 689-697. https://doi.org/10.16535/j.cnki.dlhyxb.2022-304
    Abstract (2196) PDF (1001) HTML (7)   Knowledge map   Save
    To investigate the spatial and temporal characteristics of phytoplankton functional groups and their relationship with water environmental factors in eutrophic alkaline rivers in northern cold regions, the characteristics of phytoplankton functional groups including composition, biomass, spatial and temporal distribution and relationship with water environmental factors were surveyed in 14 sampling sites in the upper, middle and lower reaches of the Hailar River basin and two major tributaries in spring (May), summer (August) and autumn (September) of 2019 by a conventional method, and multivariate statistical analysis. The results showed that there were 80 phytoplankton species in 6 families in the Hailar River basin, with the significantly higher proportion of phytoplankton functional group C in biomass from the upstream to the downstream (P<0.05). The phytoplankton in the Hailar River was divided into 20 functional groups, groups C, D, MP and X2 being important functional groups, without significant seasonal changes in important phytoplankton functional groups in the Hailar River, showing seasonal succession of C+X2+D (spring)→X2+MP+D+C (summer)→D+C+MP (autumn).The Pearson linear correlation analysis and redundancy analysis of relationship between phytoplankton functional group and the main water environmental factors affecting the phytoplankton functional groups in the Hailar River watershed were pH, total phosphorus (TP), total nitrogen (TN), and water temperature (WT), all significantly and positively correlated with the important functions groups C, D, MP, and X2. Functional groups X2 and D were found to be positively correlated with pH, TP, TN, and WT, while functional group MP to be more correlated with TP and functional group C to be more correlated with TN. It was shown that there was small difference in the composition of phytoplankton functional groups in the rivers with different latitudes, nutrient levels, and pH, without significant spatial and temporal differences in the biomass of phytoplankton functional group composition in the Hailar waters. However, there were spatial differences relatively significant, and the significant increase in proportion phytoplankton with the increase in downstream pollution was observed in functional group C.
  • Feeding differences of feeding ecology of four shark species in the tropical eastern Pacific Ocean using stable isotope Mixing model
    ZHANG Jiaxu, LI Zezheng, SHEN Yongfu, LI Yunkai
    Journal of Dalian Ocean University. 2023, 38(4): 663-670. https://doi.org/10.16535/j.cnki.dlhyxb.2022-345
    Abstract (2177) PDF (992) HTML (6)   Knowledge map   Save
    In order to probe for resource utilization of oceanic sharks, preys in the stomach contents were identified in bigeye thresher shark (Alopias superciliosus), pelagic thresher shark (Alopias pelagicus), smooth hammerhead shark (Sphyrna zygaena) and silky shark (Carcharhinus falciformis) from the tropical eastern Pacific (107°W-115°W, 17°S-6°N) by using DNA barcode, and then the contribution rates of their main prey groups were calculated using Bayesian mixing model (MixSIAR) to explore intraspecific and interspecific dietary differences. Results showed that cephalopods were paramount prey for four shark species, with small teleosts being the minimal contribution rate to smooth hammerhead and silky shark fishes, and large teleosts for bigeye thresher and pelagic thresher shark. There were different dominant food items between genders of smooth hammerhead shark, without significant difference between maturations and genders of bigeye thresher shark. For silky and pelagic thresher shark, both male and female preferred to prey cephalopods, with the significantly different contribution rates. The main prey was transferred from cephalopods to small teleosts after maturity for silky shark. The findings indicated that trophic positions of four shark species distributed in the tropical eastern Pacific Ocean were similar. However, intraspecific and interspecific dietary differences and niche segregation were observed among these species, and the resource utilizations of four shark species were different.
  • Online remediation of aged biofilters in a recirculating aquaculture system by compound probitics
    ZHANG Kang, LI Qiufen, CUI Zhengguo, HU Qingjing, WANG Qingkui
    Journal of Dalian Ocean University. 2023, 38(4): 645-651. https://doi.org/10.16535/j.cnki.dlhyxb.2022-295
    Abstract (2135) PDF (967) HTML (6)   Knowledge map   Save
    In order to solve the problem of on-line remediation of aged biofilters within a mariculture recirculating system(RAS), compound probiotics were splashed into the culture tank and aged biofilters periodically to judge the remediation effect on the aged biofilter according to the recovery of removal efficiency of nitrite, ammonia nitrogen and the recovery of microorganisms in the biofilter through monitoring the physicochemical indices of enter &effluent water and the changes in the numbers of heterotrophic bacteria and Vibrios. The results showed that the purification capacity of aged biofilters began to be reconstituted 6 days after addition of compound probiotics, and the removal efficiency of nitrite and ammonia nitrogen was found to be increased from 28.34% and 27.28% to 47.24% and 46.07%, respectively, 15 days after administration, and 10%-20% lower than those in the control. The CODMn of recovered biofilter was 21.70% lower than that of aged biofilter and that in the control (P<0.05), and the levels of nitrite, ammonia and CODMn in the whole culture system were decreased significantly (P<0.05). The abundance of heterotrophic bacteria was shown to be increased and that of Vibrio to be decreased in the whole system, with decrease in the proportion of Vibrios(P<0.05). The findings prove that on-line remediation of aged biofilters can be performed by using compound probiotics, ad that the water quality purification capacity of the biofilters can be quickly recovered, which provides a technical guarantee for the high-efficiency operation of mariculture systems and also plays a driving role for the application of compound probiotics in mariculture systems and the green health development of the mariculture industries.
  • Incorporating the migration patterns in stock assessment of Western and Central Pacific Ocean skipjack tuna (Katsuwonus pelamis)
    HUANG Yuchen, GENG Zhe, FENG Ji, SHI Yixi, ZHU Jiangfeng
    Journal of Dalian Ocean University. 2023, 38(4): 652-662. https://doi.org/10.16535/j.cnki.dlhyxb.2022-298
    Abstract (2104) PDF (944) HTML (6)   Knowledge map   Save
    The fishery of Western and Central Pacific Ocean skipjack tuna (Katsuwonus pelamis) (refer to WCPO SKJ) is divided into 8 management areas and 31 fleets in order to assess the status of the WCPO SKJ, and to explore the impact of migration patterns on skipjack tuna stock assessment. This paper focuses on the migration patterns of skipjack tuna population by season and uses age structure model Stock Synthesis 3(SS3), setting four different scenarios to simulate and analyze the migration patterns of skipjack tuna at different age stages. The stock assessment result shows that the WCPO SKJ is neither overfished (Bcur/B40%=1.9>1), nor undergoing overfishing (Fcur/F40%=0.712<1). Sensitivity analysis shows that the steepness parameter (h) strongly influences the assessment results. The higher the h value is, the more optimistic the assessment results become. Considering seasonal migration can significantly impact the stock assessment results, if the model ignores migration patterns, the impact of fishing on the stock will be underestimated. The findings indicate that consideration of seasonal and age migration in the stock assessment is a better reflection of skipjack tuna population dynamics.
  • Metabolomics analysis of effects of feeding frequency on growth in pearl gentian grouper (Epinephelus lanceolatus♂×E.fuscoguttatus♀)
    CHENG Xuewen, SHI Cunzhuo, LIU Ying, FU Songzhe, ZHANG Lei, TIAN Ye, XIONG Yuyu
    Journal of Dalian Ocean University. 2023, 38(4): 593-602. https://doi.org/10.16535/j.cnki.dlhyxb.2022-315
    Abstract (2097) PDF (954) HTML (6)   Knowledge map   Save
    In order to explore the effects of feeding frequency on growth of pearl gentian grouper (Epinephelus lanceolatus♂×E.fuscoguttatus♀) under fixed feeding rate, 180 test fish with initial body weight of (469±75)g were divided into 3 groups and reared in 3 sets of identical circulating aquaculture system. Fish in group F1 were fed once daily at 8:00 (low feeding frequency group), in group F2 were fed twice daily at 8:00 and 17:00 (control group) and in group F4 were fed 4 times daily at 8:00, 11:00, 14:00, and 17: 00 (high feeding frequency group), all at a feeding rate of 0.90% (bellow full satiation at water temperature of 25.7 ℃±1.3 ℃). Growth performance was tested at the 0 th, 17 th, 30 th, 45 th, and 60 th day of the feeding trial. The liver samples at the 60 th day were taken from group F1 and group F4 for TM broad target metabolomics analysis. The results showed that the specific growth rate (SGR) was higher in group F4 than that in group F2 and group F1. A total of 157 significantly differential metabolites were detected between group F1 and group F4, with 121 metabolites (including eicosatetraenoic acid, L-lactic acid, taurocholic acid, UDP glucose and L-thyroxine) up-regulated, and 36 metabolites (including shikimic acid, whey acid, L-aspartic acid, and guanidine acetic acid) down-regulated. The identified metabolites were annotated using KEGG Compound data base, and the annotated metabolites were mainly mapped to the arachidonic acid metabolism, amino acid biosynthesis, galactose metabolism and glycolysis/gluconeogenesis metabolic pathways.The relative concentration of L-thyroxine and guanidine acetic acid were positively and negatively correlated with the SGR, respectively. The results suggest that growth of pearl gentian grouper fed at lower feeding rate can be improved by increasing feeding frequency. The improved growth performance of fish with higer feeding frequency may relate to the increase of L-thyroxine secretion and the decrease of guanidine acetic acid synthesis.
  • Regularity of feeding acoustic signals by Pacific whiteleg shrimp (Litopenaeus vannamei) with different body length
    CAO Zhengliang, WANG Xiuxiu, LI Zhaocheng, SHEN Mengting, HU Qingsong, WU Di
    Journal of Dalian Ocean University. 2023, 38(4): 637-644. https://doi.org/10.16535/j.cnki.dlhyxb.2022-362
    Abstract (2078) PDF (933) HTML (7)   Knowledge map   Save
    A feeding acoustic trial was conducted to probe whether there were regularity and difference of the sound signals by Pacific whiteleg shrimp (Litopenaeus vannamei) with different body length of 2-3, 4-5, 6-7, 8-9, and 9-10 cm when the shrimp fed pellets and shrimp shell. Three individuals of the shrimp was placed in an acoustic test glass tank (44 cm×28 cm×30 cm) equipped with DJI underwater cameras and sound acquisition equipment consisting of an SM4 type sound recorder with a HTI-96-Min, and fed formulated diet with particle size of 1.2 mm and shrimp shell. With passive acoustic monitoring, two kinds of acoustic signals by pellets and shrimp shell from Pacific whiteleg shrimp feeding were recorded under laboratory conditions. The results showed that the peak frequency was different when different body length of Pacific whiteleg shrimp feeding pellets, with the maximum frequency about 25 kHz in small shrimp with body length of 2-3 cm, and the minimum frequency about 7 kHz in large shrimp with body length of 9-10 cm. The peak frequency was shown to be decreased with increase in the shrimp body length, which was consistent with the change in frequency range. The duration of a single pulse signal (maximum about 18 ms in the shrimp with body length of 9-10 cm, and minimum about 7 ms in the shrimp with body length of 2-3 cm) was found to be increased with the increase in shrimp body length.The duration of a single pulse signal (maximum about 13 ms in the shrimp with body length of 9-10 cm, and minimum about 6 ms in the shrimp with body length of 2-3 cm) was found to be increased with the increase in shrimp body length when different body length shrimp fed shrimp shell. The peak frequency and frequency range were related to the shrimp body length, without significant linear regularity by shrimp shell. The findings indicated that there were different in the feeding acoustic signal characteristics of Pacific whiteleg shrimp with different body length, with some regularity by pellets, without regularity by shrimp shell.
  • Farmed fish detection by improved YOLOv8 based on channel non-degradation with spatially coordinated attention
    TU Wan, YU Hong, ZHANG Peng, WEI Sixue, ZHANG Xin, YANG Zongyi, WU Junfeng, LIN Yuanshan, HU Zeyuan
    Journal of Dalian Ocean University. 2023, 38(4): 717-725. https://doi.org/10.16535/j.cnki.dlhyxb.2023-152
    Abstract (2059) PDF (972) HTML (6)   Knowledge map   Save
    In order to solve the problem of difficult fish target detection caused by fuzzy and occluded fish in actual aquaculture environments, YOLOv8-Head-ECAM, an improved YOLOv8 farmed fish detection method was established based on channel non-degradation with spatially coordinated attention ECAM (efficient coordination attention module). Firstly, the FPN (feature pyramid network) increases the large size detection head to better capture the detail information on underwater fish individuals to enhance the feature extraction ability of fish schools, and then the ECAM attention mechanism is used to reduce the interference of the fuzzy background and focuses on the key features of the fish individuals to enhance the recognition ability of fuzzy fish schools. The ablation test and comparison test were designed and carried out to verify the effectiveness of the algorithm. The results showed that the YOLOv8-Head-ECAM was improved by 2.3% in accuracy, by 1.7% in recall, and by 1.6% in mean average precision compared with the YOLOv8 model. There was 0.7% higher detection accuracy than the current farmed fish population detection models KAYOLO, 1.0% higher detection accuracy than DCM-ATM-YOLOv5, 2.4% higher detection accuracy than SK-YOLOv5, and 2.0% higher detection accuracy than ESB-YOLO. It is shown that the YOLOv8-Head-ECAM model proposed in this paper better adapts to the underwater fish blurring and occlusion and to satisfies the effectiveness of farmed fish detection.
  • Evaluation of pollution statues and the influencing factors in sediment in Bao’an Lake, Hubei Province
    LIU Jiahao, LI Yan, SHEN Dongfang, MA Shuonan, QIAO Ruiting, MAO Hui
    Journal of Dalian Ocean University. 2023, 38(4): 680-688. https://doi.org/10.16535/j.cnki.dlhyxb.2022-337
    Abstract (2058) PDF (954) HTML (7)   Knowledge map   Save
    In order to understand the situation of sediment pollution in Bao’an Lake, single-factor pollution index, comprehensive pollution index, and organic pollution index were used to analyze the pollution status of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) based on the seasonal investigation of sediments in 12 sampling sites in Bao’an Lake from July 2020 to April 2021. The results showed that there was content of (3.56±0.79)g/kg in TN, (0.57±0.20)g/kg in TP, and (59.66±16.27)g/kg in OM in the surface sediment of Bao’an Lake, with the maximal levels of TN, TP, and OM in winter, and lower in summer in the four lake areas. Such seasonal differences in sediment nutrients were primarily involved in changes in water temperature, phytoplankton, aquatic plants, microbial activity, dissolved oxygen, and external organic matter input in different seasons, with the maximal levels of both TN and OM in Biandantang located in the north Bao’an Lake and the minimal levels in the main Lake located in the south of Bao’an Lake. The maximal level of TP was observed in Xiaosihai located in the north Bao’an Lake, while the minimal in Biandantang. Aquaculture effluent from the surrounding intensive fish ponds and domestic sewage from the surrounding towns were the main factors resulting in the higher nutrients content of sediments in northern Bao’an Lake. The single-factor pollution index and the comprehensive pollution index showed that Bao’an Lake was heavily polluted, and the organic pollution index revealed an organic pollution problem. The findings indicated that the pollution status of Bao’an Lake was heavy, and maybe heavier in the future if external pollution persists. Therefore, it is urgent to carry out a series of measurements such as nutrient reduction and ecological restoration to control the eutrophication of Bao’an Lake.
  • Embryonic development and growth of larval and juvenile basa fish striped catfish (Pangasianodon hypophthalmus) and the determination of growth model
    NI Wei, CHEN Haigang, LIU Xiaoli, YU Lingyun, LI Wei, HONG Xiaoyou, LIU Yihui, ZHU Xinping
    Journal of Dalian Ocean University. 2023, 38(4): 584-592. https://doi.org/10.16535/j.cnki.dlhyxb.2022-313
    Abstract (2042) PDF (928) HTML (6)   Knowledge map   Save
    To elaborate embryonic development and growth of larval and juvenile basa fish striped catfish (Pangasianodon hypophthalmus), the fertilized eggs were obtained from spawners with body weight of 4.0-8.0 kg by hormone injection and artificial insemination and the developmental characteristics of the embryos were observed. The effects of water temperature [(24±0.5), (27±0.5), (30±0.5), and (33±0.5)]℃ and salinity of 0, 2, 4, 6, 8, 10, 11, and 12 on the embryonic development were investigated in a biochemical incubator (SPM-50). The fertilized eggs are transparent viscid egg with diameter of (1.60±0.23)mm, and the embryonic development process was divided into 7 stages at water temperature of (30±0.5)℃, including fertilized egg, cleavage, blastula, gastrula, neurula, organogenesis and hatching (totally 23 developing periods). It began to hatch after 22 hours at water temperature of (30±0.5)℃, and all hatched in 28 hours. The newly hatched larvae had total length (TL) of (4.38± 0.23)mm at the water temperature of (30±0.5)℃. It was found that 27 ℃ to 30 ℃ was of the optimum incubation water temperature,with the maximal hatching rate from 49.35% to 44.33%, and that 0 of the optimum salinity, with the maximal hatching rate of 54.33%. It was found that as the salinity increased, the hatching rate gradually decreased. Under the condition of water temperature at (30±0.5)℃, the striped catfish as a tropical fish grew and developed into the fingerling stages (30 d) via the pre-larvae (0-2 d), post larvae (3-16 d), and juvenile (17-29 d). The yolk sac was exhausted completely on the third day post hatching, with a short incubation period. The finding indicates that the striped catfish has a short incubation period and is typical warm-water freshwater fish. The optimal hatching temperature was found to be 27 to 30 ℃, and the most suitable salinity was 0. The larvae and juveniles exhibited slow growth in the early stages, but after 20 days, they started to grow rapidly, classifying them as fast-growing fish.
  • Morphological characteristics and hydrological connectivity evaluation of tidal creeks in tidal flats in Liao River Estuary
    CHEN Xu, QIN Meng’en, JIA Liyuan, ZHOU Yunhao, GUO Kaiyuan, JIANG Bo, ZHANG Mingliang
    Journal of Dalian Ocean University. 2023, 38(4): 671-679. https://doi.org/10.16535/j.cnki.dlhyxb.2022-312
    Abstract (2035) PDF (915) HTML (6)   Knowledge map   Save
    In order to understand the spatial variations in tidal creek pattrns, taking the tidal flats of the Liao River Estuary (LRE) as an example, the tidal zone was divided accurately based on the principle of tidal correction, the linear tidal creeks image was extracted using semi-automatic method, and then the tidal creeks were classify on tidal flat using the tidal creeks ordering algorithm. Also, the pattern characteristic parameters of the tidal creeks were quantified and the tidal creek network qualitatively evaluated on the tidal flat. It was found that there were obvious spatial heterogeneity in the order and average length of the tidal creeks in the surveyed area. With the increase in the order of tidal creeks, the average length of tidal creeks in the surveyed area was increased exponentially, and the number of tidal creeks decreased exponentially (R2>0.99). The total density of tidal creeks was declined dramatically as the bed elevation of tidal flats was lower. The density and frequency of tidal creeks reduced dramatically as the order of the tidal creeks were increased. The curvature of the tidal creeks was decreased as the tidal flats were closer to the open sea, with the maximal bifurcation ratio of tidal creeks in the high tidal flat of the intertidal zone (Rb=3.54), indicating that the tidal creeks were the most unstable. The connectivity of tidal creek network in the LRE was positively correlated with the total bifurcation ratio of tidal creeks and the number of island-sharped tidal creeks. The development of tidal creek network was primarily dependent on the curvature and density of the tidal creeks. In the LRE, there was the highest hydrological connectivity of the tidal creek network in the upper intertidal zone, with the maximal development and drainage efficiency of tidal creek network in the supratidal zone. The findings indicated that the tidal hydrodynamics played an important role in the spatial changes in the tidal creek form and the hydrological connectivity in the tidal wetland of LRE. Further strengthening the drainage efficiency of tidal creek network can effectively alleviate the degradation process of the tidal wetland in the LRE, and achieve the ecological restoration of the salt marsh vegetation.
  • Influence of mooring parameters on hydrodynamic characteristics of a semi-submersible fish farm
    LIU Changfeng, FENG Tengyue, WANG Ziqian, ZHANG Yu, CHEN Changping
    Journal of Dalian Ocean University. 2023, 38(4): 698-706. https://doi.org/10.16535/j.cnki.dlhyxb.2023-114
    Abstract (2024) PDF (932) HTML (6)   Knowledge map   Save
    To probe into the influence of mooring parameters on the hydrodynamic characteristics of a semi-submersible fish farm, a hydrodynamic analysis model for the fish farm subjected to waves was established by a 3D time domain boundary element method based on the impulse response function. The motion response of the fish farm and the tension of the mooring lines were calculated for different cable materials, fairlead positions, inter-group cable angles, and mooring arangements, and the application feasibility of the fish farm was assessed under the South China Sea conditions. The results showed that the unit mass per length of mooring cable top chain was decreased by 53.4% and 92.8%, the amplitude of surge motion of the fish farm decreased by 7.9% and 12.8%, respectively, the amplitude of heave motion increased by 44% and 64%, while the maximum tension of the mooring cable decreased by 7.8% and 14.4%. As the fairlead position moved up, the horizontal and heave displacements of the semi-submersible fish farm decreased, while the mooring tension increased. The intra-group cable angle was increased from 5° to 45°, the amplitude of surge motion of the fish farm decreased by 33.8%, and the maximum mooring tension increased by 5.4%. When the number of mooring cable lines increased from 8 to 12, the amplitude of heave motion of the fish farm decreased by 46.3%, and the maximum mooring tension increased by 4.9%. The findings indicated that the motion response and mooring force of the semi-submersible fish farm satisfied the requirements for storm survival and normal operation for the target aquaculture area in the South China Sea, using a configuration of 4 groups×3 cables/group consisting of “polyester fiber+steel” as the mooring line, with an intra-group angle of 22.5°.
  • Histological structure and transcriptome characteristics in liver of juvenile Amur grayling (Thymallus arcticus grubei) under high temperature stress
    FENG Chaojie, LIU Xiafei, ZHANG Ying, Lü Weihua, HAN Shicheng, ZHANG Yongquan, XU Shijian, MA Bo
    Journal of Dalian Ocean University. 2023, 38(4): 603-614. https://doi.org/10.16535/j.cnki.dlhyxb.2022-237
    Abstract (2012) PDF (943) HTML (6)   Knowledge map   Save
    In order to explore the response mechanism of Amur grayling (Thymallus arcticus grubei) under acute high temperature stress, the changes in liver histopathological structure and transcriptome expression characteristics were investigated in juvenile Amur grayling with body weight of (1.73±0.23)g exposed to 17 ℃ (high temperature group, at warming rate of 1 ℃/h) and 11 ℃ (control group) for 1, 6, 12, 24 and 48 h by histopathological method and high-throughput RNA-Seq sequencing technology. The results showed that the liver tissue structure of Amur grayling showed obvious pathological damage with the extension of stress time at 17 ℃ in high temperature group. The liver tissue had varying degrees of nuclear atrophy, deformation and vacuolization in 12 hours of stress, and the hepatocytes were most severely damaged, even cell dissolution at 48 hours of stress. A total of 214.44 Gbp of valid data were obtained by transcriptome sequencing, with an average GC content of 49.45% and a Q30 base distribution of 93.48%-96.06%. A total of 9 144 differentially expression genes (DEGs) were screened, and the number of DEGs was found to be increased first and then decreased with the extension of temperature stress. The maximal differential expression genes (7 148) were observed at 24 h of stress, 3 653 of which were up-regulated and 3 495 of which were down regulated. The GO function annotation of DEGs showed that the annotated DEGs were primarily involved in metabolism, catalysis and binding functions; KEGG enrichment analysis showed that DEGs were significantly enriched in glycolysis/gluconeogenesis, glyoxylic acid and dicarboxylic acid metabolism, fructose and mannose metabolism, protein processing in endoplasmic reticulum, ribosome and PPAR signaling pathways. Six DEGs were randomly selected for real-time fluorescent quantitative PCR validation, and the trend of gene expression was consistent with the transcriptome data. It can be seen that under the acute temperature stress, the liver tissue of Amur grayling appeared different degrees of stress damage 12 hours later. The transcriptome expression analysis revealed that the DEGs were mainly enriched in the related pathways such as immune stress and energy metabolism.
  • Pathogenicity and drug susceptibility of type ST251 high pathogenicity Aeromonas hydrophila strain straind from black carp (Mylopharyngodon piceus)
    WANG Lingling, HOU Tianmu, LI Huaming, XIANG Wei, YUAN Hanwen, LEI Liancheng, ZHANG Fuxian
    Journal of Dalian Ocean University. 2023, 38(4): 573-583. https://doi.org/10.16535/j.cnki.dlhyxb.2022-290
    Abstract (1985) PDF (926) HTML (259)   Knowledge map   Save
    In order to determine the pathogen and pathogenicity of black carp(Mylopharyngodon piceus)(body weight from 1.0 kg to 1.5 kg) with hemorrhagic disease caused in a farm in Jingzhou, Hubei Province, a dominant strain QAB5 was isolated from diseased black carp using the traditional pathogen isolation method, and its morphological characteristics, physiological and biochemical properties were investigated by 16S rRNA gene sequence, multiple sequence locus typing, extracellular enzyme activity analysis, virulence gene detection, artificial infection test, biofilm forming ability determination and drug sensitivity test. The results showed that strain QAB5 was Aeromonas hydrophila with strong pathogenicity, and had the MLST sequence type of ST251, containing hemolytic activity, protease and lipase activity, carrying six virulence genes such as aer+hly+ahp+ast+alt+act+. Artificially infected healthy black carp showed symptoms similar to naturally diseased black carp such as unresponsiveness, abdominal bleeding, anal redness and swelling, and intestinal bleeding, with median lethal dose (LD50) of 4.4×106 CFU/mL, a highly pathogenic and virulent strain. The isolated strain QAB5 was found to be sensitive to 13 antibacterial drugs including kanamycin and chloramphenicol, and moderately sensitive to penicillin; and sensitive to Chinese herbal medicines whole scorpion, Fructus Mume and clove had obvious inhibitory effect on the isolated strain QAB5 in vitro. The results showed that the isolated strain QAB5 was a virulent strain of ST251 Aeromonas hydrophila, which was the pathogen causing black carp hemorrhagic disease.Highly sensitive antibacterial drugs such as ciprofloxacin and tetracycline, combined with biofilm scavengers, are recommended for precise treatment in small doses.
  • Transcriptome analysis of regenerative process after autotomy of siphon in jackknife clam (Solen grandis)
    SUN Xuefeng, CHEN Aihua, ZHANG Zhidong, CHEN Suhua, ZHANG Yu, CAO Yi, ZHU Yanqing, YANG Jiaxin, JIANG Jianbin, WU Yangping
    Journal of Dalian Ocean University. 2023, 38(4): 564-572. https://doi.org/10.16535/j.cnki.dlhyxb.2022-335
    Abstract (1976) PDF (912) HTML (254)   Knowledge map   Save
    In order to explore the changes in transcriptome of jackknife clam (Solen grandis) after siphon autotomy, the transcriptome of jackknife clam with shell length of 8-10 cm before (control group) and 7 h, 7 d and 20 d after siphon autotomy (selection group) were analyzed by second-generation sequencing technology. The results showed that 103 909 Unigenes were obtained from the raw data after splicing and annotation, in which 30 027 Unigenes were annotated, with an annotation rate of 28.90%. The gene ontology functional enrichment results of three groups of differentially expressed genes showed that the calcium-binding items were the most enriched at 7 hours after autotomy, and the chitin-binding items were the most enriched at 7 days and 20 days after autotomy. The results of KEGG enrichment pathway showed that the jackknife clam had significantly enriched pathways only 7 days after autotomy, including amino sugar and nucleotide sugar metabolism, nitrogen metabolism, focal adhesion, lysosome and MAPK signal pathway. The time trend analysis of all differentially expressed genes in three groups showed that the top three profiles of gene enrichment were Profile5, Profile17 and Profile12. The gene ontology function annotation results of the three patterns showed that 529 genes in Profile5 were significantly enriched to ion-binding items, accounting for 53.77%, and the items with the largest number of genes enriched were receptor activity in Profile17 and chitin metabolic activity in Profile12. The RT-qPCR verification of six differentially expressed genes proved that the transcriptome sequencing results were reliable, and that preliminarily speculated various signal molecules represented by calcium ions played an important role in the process of transmitting damaged signals in the early stage of siphon regeneration (7 hours after autotomy), meanwhile the activity of various receptors was enhanced in response to the siphon regeneration process. With the progress of regeneration, the processes of substance metabolism and biosynthesis were greatly increased to meet the needs of tissue regeneration.
  • Influence of length width ratio on sewage discharge characteristics in acircular rectangular angle culture tank with double inlet pipe structure
    SHI Xianying, LI Meng, REN Xiaozhong, FENG Dejun, LIU Hangfei, ZHOU Yinxin, LIU Haibo, ZHAO Chenxu
    Journal of Dalian Ocean University. 2023, 38(4): 707-716. https://doi.org/10.16535/j.cnki.dlhyxb.2022-311
    Abstract (1953) PDF (851) HTML (6)   Knowledge map   Save
    In order to explore influence of length (long side of aquaculture tank)-width (wide side of the aquaculture tank) ratio parameters on sewage collection and discharge characteristics of the rectangular arc angle aquaculture tank with double intake pipes, a numerical calculation model (DPM discrete term model and RNG k-ε continuous phase model) for solid-liquid two-phase flows is constructed to simulate the sewage discharge characteristics in the aquaculture tank. The particle overlapping distribution method applicable to the sewage discharge simulation of the aquaculture tank with a large proportion of length and width is defined by such a model. In the study, a sewage discharge simulation experiment was carried out for two double inlet pipes (double inlet pipes arranged at the center of the long side and the center of the wide side) with L/W=1.0-1.9. The results showed that the particle removal rate reached more than 95% when the range of L/W=1.0-1.5. With the increase of the length-to-width ratio, the effect of collecting and discharging sewage the tank was gradually deteriorated. When the inlet pipe was arranged in the center of the long side with the range of L/W=1.6-1.8, the particles failed to be discharged were more concentrated in the tank. Therefore, when constructing a rectangular arc angle aquaculture tank, the tank shape of L/W=1.0-1.5 was selected for construction to achieve better sewage collecting and discharging performance and site utilization.
  • Analysis of intestinal microbial diversity of shortjaw tapertail anchovy Coilia brachygnathus in different waters
    WEN Sixin, LI Lekang , LI Yapei, LI Chenyu, GONG Xiaoling
    Journal of Dalian Ocean University. 2023, 38(4): 615-622. https://doi.org/10.16535/j.cnki.dlhyxb.2022-202
    Abstract (1910) PDF (929) HTML (7)   Knowledge map   Save
    In order to evaluate the intestinal microorganisms of fishes in different waters, the intestinal microbial composition and diversity were analyzed in whole intestinal samples of large and small with body 2 sizes of shortjaw tapertail anchovy Coilia brachygnathus weight of 100-130 g and 10-30 g, respectively, collected in Poyang Lake (PYH-L and PYH-S) (116°09′46″-116°10′03″E, 29°38′48″- 29°40′06″ N), Jiangxi Province and Qingcaosha Reservoir (QCS-L and QCS-S)(121°34′34″- 121°37′17″ E, 31°26′40″-31°28′39″ N) of the Yangtze Estuary, on late November of 2021 by 16S rRNA using high throughput sequencing technology. The results showed that there was average intestinal microbial composition OTU of 524 (large size) and 472 (small size) in Qingcaosha Reservoir and 466 (large size) and 567 (small size) in Poyang Lake. There were higher Shannon and Simpson indices in intestinal microbial diversity in QCS-L than PYH-L, while the lower Shannon and Simpson indices QCS-S were than PYH-S. The abundance of bacteria in the intestines of shortjaw tapertail anchovy was varied greatly in different waters for each phylum, with the most diverse microbial group of Burkholderia at genus level. The findings indicated that there were obvious differences in intestinal microbial diversity and abundance of shortjaw tapertail anchovy in different waters, which were most likely due to differences in their life histories, feeding transferance and environments of shortjaw tapertail anchovy.
  • Effect of in vitro passage on virulence of largemouth bass (Micropterus salmoides) ranavirus
    WANG Congxu, PAN Xiaoyi, ZHOU Kexin, MU Xuejiao, YAO Jiayun, LIN Lingyun, ZHAO Jianhua, SHEN Jinyu
    Journal of Dalian Ocean University. 2023, 38(4): 623-629. https://doi.org/10.16535/j.cnki.dlhyxb.2022-323
    Abstract (1906) PDF (921) HTML (6)   Knowledge map   Save
    The challenge test was conducted in largemouth bass (Micropterus salmoides) with body weight of (14±2)g to investigate the virulence of largemouth bass ranavirus (LMBV) in different generations. The growth kinetics of the LMBV virus were established with different titers by tissue culture infectious dose (TCID50) method, and the viral load was collected in tissue samples 1, 6, 12, 24, 36, 48, 72, 96, 120, 144, and 168 h after the challenge. The whole-genome sequences of F5 and F65 were obtained by next-generation sequencing and four virulence genes were screened out for the analysis of other genes from different strains. The results showed that lethality were found to be 60% in F5, 25% in F35 and 5% in F65 after challenge with 108.5 TCID50/mL. The higher virus load levels of the virus were detected in livers, spleens, and intestines, increase in virus loads in F65 and F35 at 96 h and 48 h post challenge. No mutations in E3, TNFR and ICP18 genes were observed among F5 and F65, and ICP46 had an amino acid mutation from aspartate to tyrosine, indicating that the stabilities of LMBV were observed during its successive passages. The mutation in ICP46 was hypothesized to be involved in the minimal virulence of F65. The findings were beneficial to verify the pathogenesis of LMBV and the application of its vaccine.
  • Synergistic stress of salinity and nitrite on metabolism of “Zebra 2” and Putian population of Manila clam (Ruditapes philippinarum)
    ZHOU Hong, GU Jing, ZHU Xianyi, GUO Yue, YANG Guojun, HUO Zhongming, WANG Hua
    Journal of Dalian Ocean University. 2023, 38(4): 630-636. https://doi.org/10.16535/j.cnki.dlhyxb.2022-299
    Abstract (1871) PDF (933) HTML (7)   Knowledge map   Save
    In order to study the synergistic stress effects of low salinity and nitrite on “Zebra 2” (shell length 27.5 mm±1.2 mm) and Putian population (shell length 31.2 mm±1.8 mm) of Manila clam (Ruditapes philippinarum), the salinity of seawater was set at 25, 20 and 15, and the concentration of nitrite nitrogen was set at 0.15, 0.30 and 0.60 mg/L with natural seawater as control at salinity of 30. The oxygen consumption rate and ammonia excretion rate were determined to investigate the effects of low salt and nitrite nitrogen single factor and their synergy on respiratory metabolism of the Manila clam. The results showed that the oxygen consumption rate of the “Zebra 2” and the Putian population increased with the decrease of salinity, and the ammonia excretion rate decreased initially and then increased. With the increasing of nitrite concentration, the oxygen consumption rate of the “Zebra 2” and the Putian population increased, but the ammonia excretion rate of the “Zebra 2” first decreased and then increased. The oxygen consumption rate of the“Zebra 2” and the Putian population increased with the increasing of nitrite concentration under nitrite stress. The ammonia excretion rate of the “Zebra 2” first decreased and then increased, while the ammonia excretion rate of the Putian population first increased and then decreased. Under the synergistic effect of low salinity and high nitrite concentration, the oxygen consumption rate and ammonia discharge rate of the “Zebra 2” and the Putian population increased. Microscopic observation of gill filament structure showed that the gill structure of the Manila clam was damaged, and respiratory epithelial cells fell off under the stress. Through the O∶N analysis of the metabolic process, we found that protein oxidation was the main power of the Manila clam, while, under the synergistic stress of low salt and high nitrite, the main power of the Manila clam was protein, supplemented by fat and carbohydrates. The findings indicate that the synergistic stress of low salt and nitrite affects the normal physiological function of gill tissue of the Manila clam, resulting in the weakening of its respiratory metabolism.
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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
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Postal code: 116023
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