Abstract:The effects of 17β-HSD11 gene on gonad development and sex hormone synthesis in H. cumingii were investigated by RACE (Rapid-amplificiantion of cDNA ends), real-time quantitative (qRT-PCR), in situ hybridization (ISH) and 17β-estradiol injection. The results showed that the full length of 17β-HSD11 cDNA was 1 134 bp, including 5' UTR 40 bp, open reading frame (ORF) 923 bp, 3' UTR 171 bp. It coded 307 amino acids. 17β-HSD11 was highly expressed in the hepatopancreas and the gonad, and the ovary was significantly higher than the testis. ISH results showed that there were hybridization signals on oocyte, follicular membrane and egg membrane. The expression of 17β-HSD11 gene was inhibited in both male and female gonads after injection of 17β-estradiol at different mass concentrations. The expression of 17β-HSD11 gene was decreased by 33.38% in ovary and 37.74% in testis after injection of 17β-estradiol at low mass concentrations. Moreover, after high mass concentration injection, the expression of 17β-HSD11 gene was decreased by 57.78% in ovary and 61.31% in testis. From the above results, it was speculated that 17β-HSD11 was related to gonadal development and estrogen synthesis in H. cumingii.

Abstract:The genes with significantly different expressions were selected from the different frequency sound gene transcriptomes of Onchidium reevesii. We compared these genes with the genes related to human auditory perception and deafness in IMPC, and the hearing-related gene NXN was discovered. The cDNA sequence of OrNXN gene was cloned by rapid amplification of cDNA ends (RACE) technology, and the sequence was analyzed by bioinformatics; real-time quantitative PCR (qPCR) technology was used to analyze the relative expression in different tissues, different frequency sounds, and different tide nodes. The results show that the length of OrNXN is 1 593 bp with 432 bp of open reading frame. OrNXN protein is encoded by 143 amino acids. The molecular mass of OrNXN is 15.57 ku. Domain prediction analysis shows that OrNXN contains a typical sulfur redox protein structure of the Thioredoxin family. The results of multiple sequence alignment and the phylogenetic tree construction showed that OrNXN has high similarity with other species. The qPCR results show that OrNXN is expressed in the intestine, ganglia, gonads and gastropods of O. reevesii. The expression is highest in the intestine, followed by ganglia. OrNXN is expressed differently at 200 and 50 Hz under different sound frequency stimulation. The relative expression level of OrNXN is different at different tidal nodes, and it basically changes with the tide water level. Studies have shown that OrNXN may respond to the low-frequency sound emitted by the tide when O. reevesii senses the tidal node rate.

Abstract:Allatostatin-A receptor gene was cloned from Litopenaeus vannamei by RACE PCR, and the sequence length is 2 650 bp, including 1 425 bp of ORF, 1 170 bp of 5'-UTR, 55 bp of 3'-UTR, encoding 474 amino acids, forming an unstable hydrophilic protein with seven transmembrane regions, and subcellular localization is mainly located on the cytoplasmic membrane. The results of homology and phylogenetic analysis showed that the Allatostatin-A receptor gene of Litopenaeus vannamei has the highest homology with Penaeus monodon and Homarus americanus, and has the closest genetic relationship.The result of multiple amino acid sequence alignment showed that the C-terminal Arg after Allatostatin-A receptor amino acid TM7 is highly conserved among different species.Real time PCR results showed that the Allatostatin-A receptor gene was expressed in multiple tissues (eyestalk, brain, stomach, hepatopancreas, gill, gonad, intestine, muscle) of female and male Litopenaeus vannamei.Except for brain tissue, the relative expression of Allatostatin-A receptor gene in female Litopenaeus vannamei is higher than that in males.With the development of Litopenaeus vannamei larvae, the relative expression of Allatostatin-A receptor gene increased.The expression level of Allatostatin-A receptor gene was the highest in the hybrid offspring of imported male shrimp and Ecuadorian wild female shrimp. It is speculated that the Allatostatin-A receptor gene may be involved in the reproduction process of Litopenaeus vannamei,and whether it is involved in the growth regulation of Litopenaeus vannamei remains to be further studied.

Abstract:Streptococcus iniae is bacterial pathogen that cause streptococcosis in many fish species. Rapid, low-cost, and user-friendly strategies are urgently needed for early disease diagnosis and timely treatment, particularly for on-site screening of pathogens in aquaculture. Loop-mediated isothermal amplification (LAMP) technique is an established diagnostic tool that can be conveniently used to screen pathogens in routine or field station laboratories. In this study, primers were designed based on the capsular polysaccharide cpsA gene to establish a visual LAMP technique for rapidly detecting S. iniae in fish culture. The results showed that the best reaction condition for LAMP is 65 ℃ for 20 min, the concentration of Mg²⁺ is 1.2 mmol/L, the concentration of dNTPs is 0.64 mmol/L, and the ratio of internal to external primers is 16∶1. The specific detection results showed that this method could specifically detect S. iniae and could not detect S. agalactiae and other 14 kinds of bacteria. The sensitivity test results showed that the sensitivity of the LAMP method is 2.12×10^-5 ng/μL, which is 100 times higher than the PCR method. The result of applicability analysis showed that the LAMP method could also correctly complete the detection in the presence of fish genome interference in the template. The LAMP detection method established in this study provides a visual, sensitive, and low cost rapid detection technique to detect S. iniae. It could be such preliminary data provided for the screening broodstock before breeding and/or the specific-pathogen-free production.

Abstract:The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and plays an important regulatory role in immune response. The AhR is central to the functions of T cells, monocytes and dendritic cells (DCs) and the production of inflammatory cytokines. To understand the roles of grass carp (Ctenopharyngodon idella) ahr1a gene, we cloned the cDNA of the ahr1a gene in grass carp. The ahr1a cDNA of C. idella is 2 893 bp in length, encoding a protein of 847 aa. It was predicted that grass carp AhR1a protein contains a typical domain of the bHLH-PAS (Period-Aryl hydrocarbon receptor nuclear translocator Single Minded, Pre-Arnt-Sim) subfamily which belongs to the helix-loop-helix (HLX) superfamily. Sequence analysis showed that the amino acid similarity and identity between grass carp AhR1a and common carp (Cyprinus carpio) were the highest. Phylogenetic tree analysis showed that the AhR1a of C. idella was clustered in a clade with homologous amino acid of goldfish (Carassius auratus), common carp and zebrafish (Danio rerio), all of which belong to the cyprinid family. Quantitative real-time PCR (qRT-PCR) analysis found that ahr1a was constitutively expressed in multiple tissues including intestine, gills, kidney, liver, head kidney, thymus, spleen, skin and brain, with the highest expression detected in the intestine and gills. Infection with Flavobacterium columnare resulted in significant decreases of the ahr1a expression in the spleen (24,48 h) and head kidney (12,24 h). In contrast, infection of grass carp reovirus (Reovirus of grass carp, GCRV) did not alter the expression levels of ahr1a in the spleen and head kidney. In the primary head kidney leukocytes, lipopolysaccride (LPS) and recombinant IL-1β dowgregulated the expression of ahr1a. In conclusion, the grass carp ahr1a gene was analyzed in this study. The results suggest that the ahr1a of C. idella may be involved in regulating inflammatory response.

Abstract:In this study, we cloned a partial cDNA sequence of Dsx (MroDsx) containing DM domain in the fresh water prawn Macrobrachium rosenbergii. The DM domain includes five conserved cysteines and two histidine, and shares 73% similarity with those of Dsx gene of the Chinese shrimp Fenneropenaeus chinensis. Quantitative PCR (qPCR) showed that MroDsx was specifically expressed in gonads, and the expression level in testis was significantly higher than that in ovary. The expression of MroDsx is particularly high in the early testis, and gradually decreased with the development of testis. In situ hybridization (ISH) results further showed MroDsx transcript is highly expressed in spermatogonium, weak in the spermatocyte and spermatid, and not expressed in spermatozoa, which is highly consistent with the results of qPCR. Based on the expression analysis of MroDsx transcript, it is implied that MroDsx may be involved in the testis development of Macrobrachium rosenbergii.

Abstract:Pyropia suborbiculata has strong high-temperature resistance, but whether it is better than the Pyropia haitanensis remains unknown. In this study, the conchospore germlings and blades of the wild strain of P. suborbiculata (PS-WT) and the cultivated strain of P. haitanensis (PH-WT10) were cultured at 23 ℃ (normal temperature) and 30 ℃ (high temperature), respectively. The results showed that: after 14 days of culture at 23 ℃, the rates of survival and rhizoid germination of conchospore germlings in PS-WT and PH-WT10 were all over 99%, and there was no significant difference between them; At 30 ℃, the rates of survival and rhizoid germination of conchospore germlings were 32.9% and 99.3% in PS-WT, the rates of survival and rhizoid germination of conchospore germlings were only 16.8% and 49.3% in PH-WT10. In addition, the percentages of conchospore germlings with more than 9 cells of PS-WT and PH-WT10 were 86.1% and 1.0% at 30 ℃, respectively. When the blades were firstly cultured at 23 ℃ for 30 days, and then cultured at 30 ℃ for another 10 days, the blades of PS-WT showed no abnormalities except slower growth and cell color turning red, and no dead cells appeared, while the blades of PH-WT10 showed significantly slower growth, lighter cell color, the chromatophore changed from stellate to diffuse, and more dead cells appeared. In addition, compared with the initial value at the beginning of the experiment, the maximum photon yield (F_v/F_m) of the blades cultured at 30 ℃ for 10 days was increased by 1.8% in PS-WT, but decreased by 34.5% in PH-WT10. The above results preliminarily confirmed that the high-temperature resistance of the conchospore germlings and blades of the wild strain of P. suborbiculata (PS-WT) was significantly better than that of the cultivated strain of P. haitanensis (PH-WT10).

Abstract:The suitable culture conditions for the growth of a newly isolated microalga Haematococcus pluvialis were investigated. The light intensity, culture temperature and inoculation density for optimal growth of the microalga were obtained as 105 μmol/(m²·s), 21 ℃and 7.5×10⁴ cells/mL respectively based on cell density as the indicator via single factor test. The growth performance (cell density) of the microalga could be predicted with the quadratic polynomial equation established by response surface method (RSM) coupled with Box -Behnken design. Light intensity, culture temperature and inoculation density as well as their binomial had significant effects on the cell density of H. pluvialis in cultivation. The weight of influence from the factors was as follows: inoculation density > light intensity > culture temperature. The combined culture conditions for optimal growth of H. pluvialis predicted by RSM were light intensity 120 μmol/(m²·s), temperature 20 ℃ and inoculation density 9.25×10⁴ cells/mL.Confirmatory test showed a cell density of 45.08 ×10⁴ cells/mL in culture was obtained under the predicted optimal combined culture conditions, which was 6.9% higher than the highest cell density of the culture under optimal culture conditions based on single factor test.

Abstract:In order to explore the adaptability of Cyprinus carpio var. qingtianensis (Paddy Field Carp) to acute dissolved oxygen changes in paddy fields, Our treatment conditions simulated the acute hypoxia and reoxygenation environment according to the tolerance parameters of Cyprinus carpio var. qingtianensis and the daily situation in the local paddy field water environment, and transcriptome analysis was conducted in brain tissue samples from normal oxygen control group(CB groups), hypoxia stress 6 h group (HB groups) and reoxygenation group(RB groups) by RNA-seq technology. The results showed that there were 1 094 differential genes in the library of the HB groups and the CB groups, of which 730 were up-regulated and 364 were down-regulated; the comparison of the RB groups and the HB groups library revealed 2 288 differential genes, of which 803 were up-regulated and 1 485 were down-regulated; the RB groups library revealed 201 differential genes, of which 80 were up-regulated and 121 were down-regulated compared with CB groups. Further, GO and KEGG analysis indicated that acute oxygen changes were involved in multiple biological pathways, mainly glycolysis/gluconeogenesis, HIF-1 signaling pathway, mTOR signaling pathway, VEGF signaling pathway and insulin signaling pathway. Finally, 6 differential genes were verified in the glycolysis/gluconeogenesis and related pathways by RT-qPCR experiments, which confirmed the reliability of the transcriptome sequencing results. These results provided basic molecular biology information for studying the physiological regulation mechanism of Cyprinus carpio var qingtianensis in the environment of acute changes in dissolved oxygen.

Abstract:To evaluate the effects of dietary proline supplement on growth, body composition and antioxidant capacity of Nibea coibor, a total of 450 Nibea coibor were randomly assigned into six treatments and fed with diets supplemented with different levels of proline (0, 5, 10, 15, 20 and 25 g/kg of dry diet) for eight weeks. After feeding, growth, body composition and antioxidant capacity of Nibea coibor were determined. The result showed that dietary proline levels had no significant effect on the growth of Nibea coibor. However, proline affected significantly the crude protein of whole-body in Nibea coibor. The optimum amount of dietary proline was estimated to be 14.73 g/kg based on the crude protein of whole-body. Increasing proline levels supplementation enhanced significantly glutathione (GSH), glutathione-peroxidase (GSH-PX) and catalase (CAT) in liver and serum of Nibea coibor and superoxide dismutase (SOD) in the serum. Contrary, increasing proline levels supplementation decreased significantly the malondialdehyde (MDA) in Nibea coibor. In conclusion, proline supplementation does not affect growth performance of Nibea coibor. However, it promotes protein synthesis and enhance antioxidant capacity of Nibea coibor.

Abstract:Four NaHCO₃ alkalinity gradients which were 3.20 mmol/L (control group), 7.73 mmol/L, 12.60 mmol/L and 16.67 mmol/L were set for breeding of 3-month-old hybrid sturgeons(Huso dauricus♀×Acipenser schrenckii♂) for 60 days to compare the effects of alkalinity on survival rate(SR), growth and serum biochemical indices of juvenile hybrid sturgeons. The results are shown as follows: that the time of first dead individual in each group was negatively correlated with alkalinity; the average survival rate of each group was 70.14%, 64.1%, 28.21% and 51.52%, respectively, the mortality of 12.60 mmol/L and 16.67 mmol/L experimental groups was higher than that of the control, with extremely significant difference; the body weight gain, body length gain ratio and feed conversion ratio of each group were extremely significantly lower than those of the control with extremely significant difference; the serum biochemical indices of 7.73 mmol/L, 12.60 mmol/L and 16.67 mmol/L groups were significantly lower than those of the control,the levels of serum total protein (TP), high density lipoprotein cholesterol (HDL) and triglyceride (TG) of 12.60 mmol/L and 16.67 mmol/L groups were significantly lower than those of 7.73 mmol/L and the control,the total cholesterol (TCHO), serum hydrogen phosphate (HCO^-₃) and serum calcium (CA) of the experimental group were significantly lower than those of the control, while the serum creatine kinase (CK) and creatinine (CREA) of the experimental group were significantly higher than those of the control with significant difference. In conclusion, high alkalinity may affect the synthesis and metabolism of protein and lipid in hybrid sturgeon, cause slow impairments to cardiac,hepar and kidney tissues, inhibit its growth and even cause individual death. It is concluded that juvenile hybrid sturgeon can be safely cultured in water with alkalinity of 7.73 mmol/L and below, and the suitable alkalinity range can be increased through domestication and adjustment of seedling specifications.

Abstract:Based on the detection data of the two farms in Fengxian District of Shanghai from 2014 to 2018 and in 2021,8 water quality indicators,including the water temperature (T), dissolved oxygen (DO), permanganate index(I_Mn), total phosphorus (TP), total nitrogen (TN),ammonia nitrogen (TAN), nitrite nitrogen (NO₂^--N) and nitrate nitrogen (NO₃^--N) were chosen to establish a prediction model based on principal component analysis (PCA) and long short-term memory (LSTM). Firstly, through principal component analysis which was used to reduce data feature extraction and dimension, I_Mn and TAN were determined to be the water quality prediction indexes to build a LSTM model based on the PCA analysis,then the PCA-LSTM model was used to predict the water quality of different ponds;Finally,comparison was carried out with a single LSTM model to verify the strengths and weaknesses of both models. The results show that the PCA-LSTM model can be used to predict I_Mn and TAN in Litopenaeus vannamei aquaculture ponds,and the prediction results are better than the single LSTM model.

Abstract:By carrying out water purification test on the sample diluent mixed by the tail water from Kunshan Sewage Treatment Plant, sewage purification effect of three submerged plants, namely Vallisneria natans, Vallisneria spinulosa and Potamogeton pectinatus, was studied in this research. For each plant, five gradients of plant density are set with a blank control group. After getting the test data, the impacts of different species and planting densities on plants’ sewage purification are analyzed from two aspects, namely pollutant-removal efficiency and instability index. The analysis results showed that: innovatively defined removal efficiency and instability index had good evaluation effect. These two indexes were respectively used to evaluate the trend of water quality change during the whole water purification test, and combined with each other to comprehensively evaluate the water ecological restoration effect of the full test cycle. The specific application has been well practiced in this paper. There were differences in the purification effects of different plants on the pollutants in the experimental sewage, and the planting density also had a certain degree of influence on the purification effects. Therefore, in the water ecological restoration project, it is suggested to select suitable submerged plant species and planting density, and pay attention to monitor the growth status of plants, so as to avoid water quality deterioration caused by vicious competition among plants.

Abstract:The investigation on the functional groups of macroinvertebrate was carried out at 12 sites in the stream of southern mountainous area of Jinan City in September 2019. The feeding evenness index (j_FD) was used to assess the ecosystem health of the stream of southern mountainous area of Jinan city. The results showed that the gather-collectors with relative abundance of 56.9% was the most dominant group among the functional groups of macroinvertebrates in this area, followed by filter feeders with relative abundance of 35.4%; the dominant groups were mainly Baetis sp., Ceratopsyche sp., Chironomus sp., Bellamya purificata, Macronychus sp. and Tanypus sp.. The j_FD value indicated that the overall ecosystem health in the stream of southern mountainous area of Jinan city was in poor condition. The regression analysis showed that there was a good correlation between j_FD and Shannon-Wiener diversity index. The redundancy analysis (RDA) showed that the relative abundance of the functional feeding groups was closely related to the total phosphorus, while the community structure of macroinvertebrate was closely related to the pH.

Abstract:To figure out the concentration of POPs(Persistent organic pollutants) in Yangtze Finless porpoise,Neophocaena asiaeorientalis, in the lower Yangtze River, we used gas chromatography mass spectrometry detector (GC-MS) to check the concentration of Hexachlorocyclohexanes(HCH)、Dichlorodiphenyltrichloroe-thanes(DDT)and Polychlorinated biphenyls(PCBs) in heart, kidney, lung, liver, muscle, skin, fat, stomach and intestine sampled from 5 Yangtze Finless porpoised dead in wild.The results showed that the overall variation ranges of HCH, DDT and PCBs were ND-0.31 μg/g, ND-19.57 μg/g and ND-1.23 μg/g, respectively.HCH was the highest in fat and the lowest in kidney, DDT was the highest in skin and the lowest in intestine, PCBs was the highest in skin, and the lowest in lung.Their average levels were higher in males than in females, and there was no correlation between different age groups.The average contents of DDT and PCBs in Yangtze River group were higher than those in the Poyang Lake group, while the average contents of HCH in the lower reaches of the Yangtze River group were opposite.Research shows that the accumulation characteristics of POPs in the Yangtze finless porpoise is related to their physiological characteristics and living environment, therefore this study could provide research material for understanding accumulation of POPs of the Yangtze finless porpoise in the downstream of Yangtze River and identifying the cause of death in the Yangtze finless porpoise, individual traceability and habitat evaluation in the future.

Abstract:In order to study what kinds of phytoplankton can grow spontaneously at high nitrogen and phosphorus levels formed from compound fishing feed decomposition, an experiment was carried out in a greenhouse during summer. The experiment included a control group with no aeration and a treatment group aerated continuously from day 12. The results revealed that the aeration significantly improved dissolved oxygen, pH, oxidation reduction potential values, chlorophyll a, and total algal biomass in the water. Chlorophyll a in the control was low but formed a peak from days 10 to 17, while that in the treatment reached its highest value of (1 169.57 ± 1 133.01) μg/L on day 27, and the highest algal biomass was (279.07±339.83) mg/L on day 25. Green algae particularly Scenedesmus spp. dominated in the treatment, and green algae particularly Chlamydomonas spp. and Chroococcus sp. dominated in the control, from days 21 to 31. Therefore, green algae dominated under aeration at high nutrient level of 3.8-22.1 mg/L total nitrogen and 2.1-16.9 mg/L total phosphorus, which was derived from decomposing compound fish feed.

Abstract:To explore the bacterial community structure and its relationship with environmental factors, the water and sediment in the purification channel of aquaculture tailwater in the Tiaozini reclamation area were monitored. The results showed that there were significant differences in water quality between different months and physicochemical properties of sediments at different sites. Judging by the total nitrogen (TN) and total phosphorus (TP), the river water was at a level of eutrophication, but it met the second-level discharge standard of water from aquaculture ponds in Jiangsu Province. Olsen-P indicated that the sediments were not at a high nutrient level. The changes of bacterial community composition in water and sediments were consistent with physicochemical properties, and significant differences were found in the diversity, richness, and composition of bacterial communities in the two environments. Cyanobacteria was one of the dominant bacteria in water, with a relative abundance of 39.33% in September. Cyanobium_PCC-6307 occupied the highest abundance in both water (13.34%) and sediments (8.15%) and had the greatest effect on bacterial communities. Water temperature (T), TN, soluble active phosphate (SRP), and permanganate index (COD_Mn) were significantly correlated with bacterial communities. Except TN, the other 3 indicators were positively correlated with Cyanobium_PCC-6307. Water soluble phosphorus (WSP), readily desorbable phosphate (RDP), and total carbon (TC) in the sediments were significantly correlated with bacterial communities, and WSP and RDP were positively correlated with Cyanobium_PCC-6307. To limit the accumulation of Cyanobium_PCC-6307 in the channels, the control of phosphorus in aquaculture tailwater should be strengthened. This study provides a reference for the regulation of tailwater and healthy development of aquaculture in coastal reclamation areas.

Abstract:Seafloor macrolitter has been recognized as a major part of marine litter, while it is the least investigated fraction of marine litter.Seafloor macrolitter is not biodegradable and transferable. Therefore, it can directly alter the marine environment and bottom sediment, and indirectly threat the health of marine ecosystem by impacting the survival and growth of marine organisms. This study retrospected the studies on the ecological impacts of seafloor macrolitter from the perspective of colonization, entanglement,encirclement and ingestion, and pointed to future developments that are required to address the estimation of seafloor macrolitter. Knowledge of this study could provide scientific support for the evaluation of potential impacts on marine biodiversity, as well as the monitor and management of seafloor macrolitter.

Abstract:The acoustic assessment of fishery resources is one of the important research contents in the field of fisheries science, and it has become an important method to estimate the fishery biomass, in which the establishment of acoustic scattering model of fish body is the core technology. In this paper, the acoustic assessment techniques of fishery resources were summarized, and the theoretical basis and applicable range of 10 kinds of acoustic scattering models in the two categories of datum and non-datum were summarized, the application of acoustic scattering model in the study of target intensity of individual fish and fish school was reviewed, and the application of acoustic scattering model in fish species classification and recognition was summarized. It is concluded that in the future research, the method of combining acoustic scattering modeling, theoretical analysis, computer simulation and experimental data verification should be adopted, which can be based on the information of fish schools obtained by broadband fish detection sonar, and a more accurate and perfect acoustic assessment technique should be constructed to provide a reliable research method for reasonable estimation and exploitation of fishery resources.

Abstract:Southern elephant seal (Mirounga leonina) is an important predator in the Antarctic marine ecosystem, and its behavioral characteristics are important in ecological and biological oceanography research, but the regional behavioral characteristics of southern elephant seal in Kerguelen have rarely been studied. In this study, the dataset of CTD attached to southern elephant seals from the northern Kerguelen Plateau were used to predict the horizontal movement of southern elephant seals using a switching-state space model (SSSM), and the water masses preferred for their foraging use and diving characteristics were analyzed. The results showed that, horizontally, the uneven distribution of food resources drove southern elephant seals to migrate to more productive areas, and they mainly gathered in three more productive areas to forage, among which the eastern part of Kerguelen Plateau was the target of most southern elephant seals; vertically, the diving behavior of southern elephant seal was not affected by light level and the movement performance varied significantly among individuals, but had a combination of high frequency and depth, This linited the feeding area to the winter water (WW), which may be the result of a trade-off strategy between the distribution of predation targets and inter specific competition. This study enriches the knowledge of post-breeding behavior of southern elephant seals in Kerguelen Islands, and may provide a better understanding of the behavior and ecological characteristics of marine predators in the future, and thus further illustrate the function of the Antarctic ecosystem.

Abstract:The South China Sea is the largest semi-enclosed marginal sea in the Western Pacific.It is also a core area affected by the Southeast Asian monsoon. Due to its special geographic location, the hydrological characteristics are extremely complex in the northern South China Sea. In summer, driven by the southwest monsoon, there are seasonal coastal upwellings in the northern shelf of the South China Sea, which mainly include the coastal upwellings of East Guangdong and Qiongdong. In addition, the diluted water from the Pearl River Estuary with high nutrients also has an important impact on the ecological characteristics in the northern South China Sea.This study is based on the data collected from 23 stations set up in the northern South China Sea during summertime of 2012. The larval and juvenile fish samples were collected by the vertical trawl survey with WP2 plankton net (net diameter 57 cm, net length 271 cm, mesh 200 μm). The species composition and quantity distribution of larvae fish and juveniles were studied, and the association between them and environmental factors was investigated, and the correlation between the hydrological characteristics of the northern South China Sea and the distribution and assemblages of fish larvae and juveniles was analyzed. A total of 230 fish larvae and juveniles were collected, belonging to 11 orders, 33 families, and 77 species, of which 46 species were identified. The most diverse order was Perciformes, with 24 species in 16 families, accounting for 31.17% of the species of fish larvae and juveniles in the surveyed sea area. Followed by Myctophiformes and Stomiiformes, 18 species in 1 family and 12 species in 4 families, respectively. The fish larvae and juveniles of Myctophidae, Phosichthyidae and Gonostomatidae accounted for about 50% of the total catch of fish larvae and juveniles.These results are consistent with the results of many previous surveys, which indicates that the species composition of fish larvae and juveniles in the South China Sea has not changed much.The changes in the number of fish larvae and juveniles among the stations in the surveyed sea area are more consistent with the change trend of the richness index (D). In general, the fish larval and juvenile fish community structure in the surveyed sea area is relatively stable.In summer, abundance of fish larvae and juveniles was related to environmental factors, such as temperature, salinity, chlorophyll-a mass concentration. Three peaks of the abundance were found, in eastern Hainan Island,where the coastal upwelling occurred,the diluted water from the Pearl River, and coastal water of the Paracel Islands. At the same time, the canonical correlation analysis (CCA) results also showed that the temporal and spatial distribution of fish larvae and juveniles in the northern South China Sea is closely related to surface sea temperature (SST) and chlorophyll a (Chl.a) mass concentration.Cluster analysis showed that the fish larvae and juveniles assemblage could be divided into oceanic group and offshore group.

Abstract:In recent years fisheries management has gradually shifted from single-species management mode to ecosystem-based management mode. Due to the complexity, however, the ecosystem-based management has not been widely studied and implemented. Based on public databases in the Indian Ocean Tuna Commission (IOTC), Fishbase and other resources, a LeMaRns ecosystem model (Length-based Multi-species analysis by numerical simulation in R) was developed based on 19 major species in the Indian Ocean tuna fisheries, and changes of species and ecosystem structure at different fishing levels of four fishery types were predicted. The results showed that fishing would reduce the stock biomass, affect the interspecific relationship and further lead to the changes of stock biomass of other species. Large fish indicator (LFI) and mean maximum length (MML) are most sensitive to longline, and the decrease of the two indicators indicated that the proportion of large individual fish in the ecosystem decreases and the proportion of small individual fish increases, which may have a negative impact on the stability of the ecosystem and should be considered in fishery management. The study suggests that fishing has a negative impact on the ecosystem structure, however, fishery type imposed the impact differently with respect to various species. This should be taken into account when implementing ecosystem based management. Under the scenario of two times of recent fishing effort (2 × E_2010-2019), no stock was predicted to be in a state of collapse, and the relative stock biomass of skipjack tuna, albacore tuna, yellowfin tuna and bigeye tuna ranged 0.6-0.7, 0.6-0.7, 0.7-0.8 and 0.6-0.7, respectively, remained at a relatively high level, indicating that the stocks are in a healthy state. Finally, in order to better apply the LeMaRns model to the pelagic ecosystem system, several suggestions were made for further research: structural improvement of the LeMaRns model to better suit the actual situation, and conducting food web surveys and biological studies to ensure accurate data, and incorporating environmental factors, etc.

Abstract:As a common phenomenon after artificial reefs are put into operation, reef settlement will have an impact on the flow field around artificial reefs.In order to study the change of flow field effect under different settlement of porous square artificial reef, the flow field around single reef to five different settlement degrees was simulated by using computational fluid dynamics (CFD) technology and Fluent software when the fixed incoming flow velocity was 0.8 m/s.The results showed that compared with the case without settlement (initial state), when the settlement degree was 20%, the maximum height of upwelling decreased by about 1m, the maximum upwelling velocity increased by about 0.015 m/s, the lateral velocity increase area (greater than the incoming velocity) expands to about 1.5 times, at the same time, the permeable area of the reef back flow surface increased, and the back vortex area moved about 2 m along the flow direction. The flow field around the reef becomes more complex to some extent;When the settlement degree is 40%, the maximum value of upwelling velocity decreases by about 0.01 m/s compared with the initial state, and the increasing area of lateral flow is basically the same. At this time, the permeable area of reef back flow surface changes greatly, and there is a trend of counterclockwise vortex; When the settlement reaches 60%, the flow field effect around the reef begins to decrease significantly, the maximum height of the upwelling decreases by about 3.2 m compared with the initial state, the maximum velocity of the upwelling decreases by about 0.6 m/s, the distance between the lateral velocity increasing area and the wall shortens by about 0.4 m, and the back vortex area seemed disappear;When the settlement reaches 80%, the flow field effect of reef body basically lost.The results showed that for the porous square artificial reef, the artificial reef can still play a good flow field effect when the settlement degree is less than 40%; When the settlement of the reef reaches 60%, the complexity of the flow field around the reef is obviously lost compared with the initial state. Then, with the increase of the settlement depth, the flow field effect of the reef gradually disappears.

Abstract:A sulfated fucoidan named as SF0, was isolated from Sargassum pallidum with hot water extraction and further purified by a strong anion exchange column and a gel filtration column. SF0 was further fractionated into three fractions SF1, SF2 and SF3 by stepwise partial acid hydrolysis. The content of sulfated group and molecular weight were decreased from SF0 to SF3. The structural features and anti-influenza A (H1N1) virus activities of all these fractions were determined. Results showed that SF0 was a homogeneous polysaccharide with a large molecular weight of 628.1 ku. It was mainly composed of mannose, glucuronic acid, glucose, galactose, xylose and fucose, in the molar ratio of 10.8∶8.3∶3.0∶21.1∶21.2∶35.6, SF0 has a backbone composed of α-D-1,2-Manp and β-D-1,4-GlcAp disaccharide repeat unit. The anti-influenza A (H1N1) virus assay showed that all these fractions inhibited H1N1 virus replication in MDCK cells. Moreover, the fraction SF3 with the low molecular weight had better activity than original fraction. It suggested that the anti-H1N1 virus activity of fucoidan was related to its fine structure and molecular weight.

Abstract:Cladophora sp. are cosmopolitans inhabiting waters with different salinity, from freshwater to hypersaline. Eutrophication of marine and inland waters results in the huge development of filamentous green algae, which reach high biomass and occupy large areas in different water bodies. In this study, we explored the effects of different configurations, extraction methods and concentrations of plant extracts on the growth and photosynthetic system of Cladophora sp. The results showed that the fresh weight of Cladophora sp. was significantly inhibited by Ginkgo biloba, willow and two compound leaves extracts The extract of Ginkgo biloba leaves had the best inhibitory effect on Cladophora sp., with a growth inhibition rate of 66.65% at 96 h. Furthermore, the extract of Ginkgo biloba leaves also had a higher inhibitory effect on the photosynthetic system of Cladophora sp. . At 96 h, the inhibition rates of maximum PSⅡ light energy conversion efficiency (F_v/F_m), actual photochemical efficiency (Yield) and non-photochemical quenching parameters (NPQ) reached 96.69 %, 99.22 % and 78.06 %, respectively. The experimental results of different extracts on the algal inhibition of Ginkgo biloba leaf extracts showed that ethanol and acetone extracts showed stronger inhibition than chloroform and water extracts. Among them, ethanol extracts had the strongest inhibitory effect on the photosynthetic system of Cladophora sp., with the inhibition rates of F_v/F_m, Yield and initial slope of fast light curve (α) all reached 99% at 48 h. In addition, the results showed that there was a positive correlation between the extract concentration and algae inhibition effect. 3.00 g/L and 6.00 g/L groups had significant inhibitory effect on Cladophora sp.. The inhibitory rates of F_v/F_m, Yield and α of 6.00 g/L at 96 h were 99.87 %, 100 % and 100 % respectively. These results suggest that plant leaves extracts may be useful in controlling Cladophora sp..

Abstract:Rivers transport large amounts of terrestrial organic matter, inorganic matter, and microorganisms to the ocean, where they are deposited into offshore basins.With the gradual accumulation of terrigenous and marine sediments in the basin, these terrigenous microorganisms were buried and gradually evolved into a part of the inherent microbial community in the sediments. It is an ideal ecosystem for studying the adaptation and evolution of microbial environment.A Gram-positive bacterium Virgibacilus pantothenticus 19R1-5(19R) was successfully isolated from a coal seam core (1 999 mbsf, meter below the seafloor) in the Western Pacific Ocean during the International Ocean Drilling Program (IODP) Expedition 337 by our research group.The 16S rRNA sequence of 19R was 100% similar to that of Virgibacilus pantothenticus DSM 26(26^T) isolated from land-based soil, and the homology of DNA hybridization was 91.7%.We studied the origin and metabolic potential of 19R and 26^T from the perspective of comparative genomes.The results show that the 19R isolated from the deep seabed originated from the land. Compared with 26^T, 19R has three additional PTS systems, suggesting that 19R has stronger sugar utilization capacity, which enables it to adapt to the special nutritional environment in deep biosphere.The results of this study are of great significance for exploring the origin of microorganisms in the deep seabed biosphere and their role in the deep sea material circulation.

Abstract:Marine cultural industry, as a new engine for the development of marine industry, plays an important role in promoting the upgrading of marine industry and extending the marine industrial chain.Under the background of experiential economics, this paper studies the development status of marine cultural industry in Lingang Special Area on the basis of obtaining relevant information, and uses ASEB grid to systematically sort out and analyze the experiential development.It is found that Lingang has inherent abundant marine culture, fishery tourism resources and location advantages, but these resources have insufficient experience,poor brand image and single development mode.This constrains the development of the region.To this end, the article puts forward the following suggestions:1.Highlight the experience of marine cultural industry;2.Shape the experience image of marine cultural industry;3.Optimize the brand of marine cultural experience to enhance its popularity and influence;4.Establish a series of leisure experience industries based on Dishui Lake and promote the agglomeration effect of marine cultural industry;5. Strengthen the support of local universities for marine culture industry. This will contribute to the rational development of marine cultural industries in the central district of Lingang Special Area in the future, so as to provide reference for the development of related industries in emerging coastal cities.