Abstract:2-Methylisoborneol (2-MIB) is a volatile organic compound produced by a variety of actinomycetes, soil organisms and cyanobacteria, which is widely found in water bodies. To explore the effects of 2-MIB on fish, in this study, zebrafish were exposed to 42 ng/L 2-MIB for 24 hours. Comparative transcriptome analysis of gill tissues revealed that there were 163 genes up-regulated and 565 genes down-regulated significantly in the 2-MIB treatment group. KEGG pathway enrichment showed that oxidative phosphorylation related biochemical processes were up-regulated, while immune-related signaling pathways such as Toll-like receptor signaling pathway was down-regulated. RT-qPCR further showed that 2-MIB significantly up-regulated the expression of oxidative phosphorylation related genes, such as ndufb7, mt-cyb, mt-nd4, mt-nd6, mt-co2 and mt-atp6, while the immune-related genes rela, cd40, ikbkb, mapk8b, mapk3 and ripk1l were significantly down-regulated. Indeed, the activity of superoxide dismutase (SOD) increased in gills and liver after 2-MIB exposure. This study shows that 2-MIB can raise the level of oxidative phosphorylation in zebrafish and decrease the expression of genes related to Toll-like receptor signaling pathway.

Abstract:To study the biological function of zebrafish ribosomal proteins in response to hypoxic stress, transcriptome analysis was performed on the gill tissues of Danio rerio under hypoxic and normoxic conditions, and the gene expression differences of ribosomal protein family genes in the gill of D. rerio were compared. The results showed that the expression levels of 60 ribosomal protein genes in zebrafish gill tissues were significantly up-regulated at two different concentrations of hypoxia stress, which included 35 large subunit ribosomal protein genes and 25 small subunit ribosomal protein genes. Among the top 15 pathways enriched by the significantly deferentially expressed genes in the zebrafish gills under hypoxia stress, all included the ribosomal protein genes, and 5 were related to ribosomal protein assembly and synthesis. In the enriched “translation” GO term, 44 ribosomal protein genes were included. In addition, the target genes of 60 significantly up-regulated ribosomal protein genes were predicted by two significantly down-expressed miRNA in zebrafish gills under hypoxia stress, which were screened in our previous study. The results show that miR-455-3p can target both ribosomal protein genes rpl13 and rplp1, which might be involved in the adaptation to the hypoxia environment.

Abstract:Intermuscular bones (IBs) exist in the intermuscular septums of some species of teleosts. MsxC (muscle segment homeobox C) gene, a member of Hox gene family, was postulated to potentially play a role during the development of intermuscular bone in Hemibarbus labeo. In this study, we deleted MsxC gene in zebrafish genome by CRISPR/Cas9 technology to create the MsxC^-/- strain. Compared with wild-type zebrafish, MsxC^-/- zebrafish had shorter IBs in rear part of body, where both epineurals and epipleurals were shortened by more than 15% on average. However, there was no significant difference in the length of IBs in the anterior part of trunk. We also found less fast muscle fibers nearby septum in MsxC^-/- zebrafish, especially in rear part of body. On the contrary, more slow muscle fibers were found in MsxC^-/- zebrafish. Compared with wild type, the area of slow muscle in rear part of MsxC^-/- zebrafish was increased by 2.22%(P<0.01), whereas the area of trunk anterior part was increased by 0.97% (P<0.05). All these results suggested that the deletion of MsxC gene affected both the formation of IBs and the development of axial muscle.

Abstract:Corticotropin-releasing hormone (CRH) plays a key regulatory role in coordinating the regulation of endocrine, autonomic nervous activity, immunity, osmoregulation and food intake in teleost. However, a direct effect of CRH on steroidogenesis in follicles of zebrafish remains unkown. Here, the expression of CRH receptors (CRHRs) and genes related to steroidogenesis in cultured zebrafish ovarian follicles were analyzed by real-time quantitative PCR. The contents of estradiol and progesterone in culture medium were analyzed by radioimmunoassay, respectively. The mRNA levels of CRHR1, but not CRHR2, were significantly up-regulated in both CRHα and CRHβ treatments compared with control group. Treatment with CRHβ stimulated the expression of cyp19a1a. However, other genes related to steroidogenesis had no apparent changes after being treated with CRHα and CRHβ. The protein levels of estradiol were significantly decreased after CRHα or CRHβ treatments, but no effect was found on progesterone. Taken together, these results suggested that CRH might reduce the synthesis of estradiol by regulating the expression of genes related to steroidogenesis through CRHR1.

Abstract:A total of 1871 proteins were identified by iTRAQ and bioinformatics analysis, among which 119 differentially expressed proteins (P<0.05), including 74 up-regulated proteins and 45 down-regulated proteins. And 37 immune-related proteins were screened, including 19 up-regulated proteins and 18 down-regulated proteins, which are mainly enriched in Notch, Hippo, NF-κB, TGF-β and some other signaling pathways which related to the immunoglobulin, wound healing and inflammation. Up-regulated proteins such as MRC1 LBP, EPX, FCGBP, and down-regulated proteins like CD109, CNN3, NOTCH3, LAMB2 had the similar trend as the mRNA expression level in tissues 5, 20, 50,90 days after inserting. It is speculated that in the process of pearl sac formation, molluscs may protect cells from the damage by immune mechanism and inflammation through these differential proteins, and promote the fusion of pearl sac and outer mantle. This study provided basic data for understanding the immune response caused by Hyriopsis cumingii nucleus insertion.

Abstract:In order to study the effects of fermented soybean meal replacing of fish meal on the growth, feed utilization, apparent digestibility and digestive enzyme activity of largemouth bass (Micropterus salmoides), we employed soybean meal with aerobic fermentation by Bacillus subtilis as a partial substitute for fish meal with equal nitrogen and equal energy. 0% (FM group), 10% (FSM10 group), 15% (FSM20 group), 20% (FSM30 group) and 25% (FSM40 group) of fermented soybean were respectively used for replacing 0%, 10%, 20%, 30% and 40% fish meal. Largemouth bass, initial weight, (19.83±0.33)g were randomly divided into 5 groups, each group had 3 replicates and every replicate contained 30 fish. The largemouth bass were fed twice a day (7:00 and 17:00) for 75 days. The results showed that: there were no significant differences in the feed coefficients of five groups (P>0.05), however, the final average weight and specific growth rate of FSM20 and FSM30 groups were significantly higher than those of other groups (P<0.05); proteins efficiency of each group showed no significant differences (P>0.05), the food intake of FSM groups were significantly higher than that of the FM groups (P<0.05), and the protein deposition rate and fat deposition rate of the FSM40 group were significantly lower than those of the other groups (P<0.05); there were no significant differences in whole fish crude protein in each group, and the maximum value appeared in FSM20 group (P<0.05), and crude fat of whole fish in FSM groups was significantly lower than that in FM groups (P<0.05); there were no significant differences in protein digestibility and fat digestibility between all the groups (P>0.05),and apparent digestibility of dry matter of FSM30 and FSM40 were significantly lower than that of other groups (P<0.05); there were no significant differences in the activities of protease, amylase and lipase between the FSM groups and the FM groups while fermented soybean meal was less than 15%.

Abstract:In order to study the effects of temperature on the growth and reproductive performance of Macrobrachium nipponense from zoea to postlarvae, the newly hatched zoea were cultured at a constant water temperature of 21 ℃, 26 ℃ or 31 ℃ under laboratory conditions respectively for 90 d.The results showed that the ontogeny rate of individual increased with the increase of temperature. The time required for the complete metamorphosis of zoea at 21 ℃, 26 ℃ and 31 ℃ into postlarvae were (54.7±1.5) d, (24.0±1.0) d and (19.3±0.6) d, respectively; The water temperature does not affect and the survival rate of zoea, but affects the survival rate of zoea metamorphosed into postlarvae, and the survival rate of zoea metamorphosed into postlarvae of 21 ℃ group was significantly lower than that of 26 ℃ group and 31 ℃ group (P<0.05); Temperature affects the gonadal development of M. nipponense. During the 90d test period, there were no ovarian individuals in the 21 ℃ group, the first sexually mature individuals in the 31 ℃ group, and time of first berried female appeared on(55.7±5.5) d, which was about 17 d earlier than that at 26 ℃; The amount of berried eggs per female for the first time in the 26 ℃ group was significantly higher than that in the 31 ℃ group(P<0.05), but there was no significant difference in relative fecundity between the two groups (P>0.05). At the end of the experiment, the largest body length and body mass of M. nipponense appeared in the 26 ℃ group, which was significantly higher than that in the 21 ℃ group (P<0.05). This study suggests that temperature affects the growth and development of M. nipponense, but does not change its relative fecundity, and high temperature will promote the miniaturization of sexually mature individuals.

Abstract:To investigate the effects of cadmium (Cd) and low pH stress on antioxidant defense ability of the Chinese Mitten Crab(Eriocheir sinensis), two experimental groups with different pH values (7.8, 6.5), and three experimental groups with different Cd²⁺ concentrations (0 mg/L, 1.45 mg/L and 2.9 mg/L), were set and exposed for 7 d, 14 d, and 21 d, respectively. The effects of cadmium and low pH stress on total hemocyte counts (THC), serum superoxide dismutase (SOD) activity, catalase (CAT) activity, total antioxidant capacity (T-AOC), malondialdehyde (MDA) content and four immune related genes (glutathione peroxidase (GPx), glutathione S-transferase (GST), heat shock protein 70 (HSP70), lysozyme (LZM) mRNA in hepatopancreas of Eriocheir sinensis were studied. The results showed that THC decreased significantly with the increase of Cd concentration, and THC at pH 6.5 was lower than that at pH 7.8. When the pH value was 7.8, with the increase of cadmium concentration, the activities of SOD and T-AOC in serum increased first and then decreased, while the activities of CAT (except the 7th day) and the content of MDA increased gradually. The activities of SOD, CAT, and T-AOC were significantly lower than those of pH 7.8 (P<0.05). During the whole experiment, the content of MDA at 2.9 mg/L and pH 6.5 was significantly higher than that at pH 7.8 (P<0.05). When pH value was 7.8, the mRNA expression levels of GPx, GST, HSP70 and LZM increased gradually with the increase of cadmium concentration. When cadmium concentration was 2.9 mg/L for 21 days, the gene expression levels reached the highest. On the 14th and 21st day, the expression of GPx and GST mRNA at 2.9 mg/L and pH 6.5 of cadmium was significantly decreased, which was significantly lower than that at pH 7.8 of the same concentration (P<0.05), while the expression of HSP70 and LZM mRNA was significantly decreased only on the 21st day, which was also significantly lower than that at pH 7.8 of the same concentration (P<0.05). In general, the activity and content of antioxidant enzymes and the mRNA expression of related genes were up-regulated or down regulated in response to oxidative stress. The effect of low pH and cadmium on the antioxidant defense of Eriocheir sinensis was much greater than that of single factor, especially high concentration of cadmium (2.9 mg/L). The results provide a theoretical basis for the future study of the impact of water acidification and heavy metal pollution on crustaceans.

Abstract:To explore the relationship between gut microbiota and growth of Chinese mitten crab(Eriocheir sinensis) at different water temperatures, the growth performance was tested and gut microbiota composition was analyzed by 16S rRNA high-throughput sequencing of this crab cultured at four water temperatures(26 ℃, 29 ℃, 32 ℃, and 35 ℃). The results showed that the molting times of Chinese mitten crab in four water temperature groups were 2, 2, 2 and 1 respectively, the survival rates were 82.81%, 84.38%, 87.50%, 25.00% respectively, the average molting interval shortened gradually with the increase of water temperature, the molting weight gain rate increased first and then decreased with the water temperature increasing, and the condition factor had no significant difference among different water temperatures (P>0.05). The sequencing results of the gut microbiota showed that 929, 744, 680 and 518 Operational Taxonomic Units(OTU) were obtained for the 26 ℃, 29 ℃, 32 ℃ and 35 ℃ water temperature groups, respectively.The α diversity results showed that the abundance and diversity of gut microbiota decreased with the increase of water temperature,and the results of β diversity analysis showed that there were significant differences (P<0.05) for the gut microbiota composition among the four water temperature groups. At the phylum level, the dominant gut microbiota for the four water temperature groups were Firmicutes, Bacteroidota and Proteobacteria, which accounted for 96.26% of the total microbiota, for Patescibacteria(0.92%)and Verrucomicrobia(0.35%)in the 26 ℃ group, Firmicutes(58.04%) and Actinobacteriota(3.44%)in the 29 ℃ group, and Bacteroidota(41.84%) in the 32 ℃ group,and the abundance of their gut microbiota was significantly higher than that of other water temperature groups (P<0.05).At the genus level, Gemmobacter(3.55%)in the 26 ℃ group,Citrobacter(3.56%)in the 29 ℃ group,Pragia(8.47%)in the 32 ℃ group, Psuedomonas(8.77%) in the 35 ℃ group, and the abundance of their gut microbiota was significantly higher than that of other water temperature groups (P<0.05). The results of this study indicated that the best water temperature should be about 30℃ for growth of Chinese mitten crab, the diversity and abundance of gut microbiota would decrease with the increase of water temperature, and under high temperature condition, some harmful flora, such as Campilobacterota and Malaciobacter, would increase and affect the molting and growth of Chinese mitten crabs.

Abstract:Rhopilema esculenta is a common jellyfish with high economic value in the coastal areas in China. The ephyra is an important stage of its growth and development. Under laboratory conditions, the feeding frequency (1, 2 and 3 times/d) of different specifications [D≤5; 5<D<9; D≥9 (D is the bell diameter)], light time (0 h, 8 h, 12 h, 16 h and 24 h/d) and light intensity [natural light (1 405 lx) and weak light (605 lx)] were used to study the effects of four factors on the growth of the ephyra. The results showed that the growth requirements of the ephyra with bell diameter of about 7 mm could be satisfied by feeding them twice a day under the conditions of temperature 21 ℃, salinity 20, pH 7.5 and dissolved oxygen 8.5-9.0 mg/L. The smaller the bell diameter, the higher the growth rate and the faster the growth rate. There were significant differences in the growth rate of ephyra at 0 h, 8 h, 24 h/d and 12 h, 16 h/d (P<0.05). There was no significant difference between 0 h, 8 h and 24 h/d (P>0.05). There was no significant difference between 12 h and 16 h (P>0.05), and 12 h/d light was the most favorable for the growth of ephyra.There was no significant difference between natural light and weak light on the growth of ephyra(P>0.05). The conclusion provides a scientific basis for the physiological study of growth stage and breeding technology of ephyra.

Abstract:In 2017, a large reservoir named Qingcaosha in Shanghai built an ecological slope protection. In order to explore its impact on the structure of the phytoplankton community, a monthly survey and comparison study of the phytoplankton community in the ecological slope protection area of the reservoir and the control area in the reservoir was carried out in 2018. A total of 201 species of phytoplankton in the ecological slope protection area and 194 species in the control area in the reservoir were identified. The species in the two regions were moderately similar, and the species composition was both Chlorophyta-Bacillariophyta-Cyanophytatype. The dominant species in the ecological slope protection area and the control area of the reservoir mainly belonged to Chlorophyta and Bacillariophyta, which were basically the same. The dominant species with a high degree of dominance were Aphanocapsa sp., Pseudanabaena limnetica, and Cyclotella sp. and Aulacoseira ambigua. The annual mean biological density and biomass of the community atecological slope protection areawere (578.46±455.30)×10⁴ cells/L and (1.55±1.03) mg/L, respectively, and those of the control area in the reservoir were respectively (663.46±588.67)×10⁴ cells/L and (1.61±0.98) mg/L. There was no significant difference in phytoplankton stock between the two areas (P>0.05). The PCOA analysis of the principal coordinates showed that there was no significant difference in phytoplankton community structure between the ecological slope protection area and the control area in the reservoir (P>0.05). The above results all demonstrate that the construction of the ecological slope protection has little impact on the phytoplankton community of the reservoir.

Abstract:The study was based on the rice-crab culture of integrated system to analyze phytoplankton and environmental factors at the water inlet, middle and outlet of paddies in the village of Helan, Ningxia. The rice species was Qiuyou 88, and the crab variety was Eriocheir sinensis. In the experiment, four paddies (paddy 3, 6, 7 and 10) were irrigated with fish pond tail water (experimental group) and one paddy (paddy 8) was irrigated with water from Yellow River (control group).The results showed that A total of 235 phytoplankton species were identified from 8 phyla throughout four periods in experiment group,among which 153 species from 8 phyla in paddy 3, 147 species from 8 phyla in paddy 6, 143 species from 7 phyla in paddy 7 and 159 species from 8 phyla in paddy 10. A total of 127 species from 7 phyla were identified in the control group. The average density of the experimental group was higher than that of the control group (P<0.05); A total of 13 dominant species were found in the experimental group and 9 dominant species were found in the control group, all of which were dominated by Cyanobacteria. The diversity index of paddy irrigated fish pond tail water was higher than that irrigated Yellow River water, which indicated that the phytoplankton community structure of the paddy irrigated fish pond was more perfect and stable. There was no significant difference in total alkalinity and salinity between the experimental group and the control group (P>0.05), but there was significant difference in transparency, water temperature, phosphate, pH,dissolved oxygen, nitrite and ammonia nitrogen between the experimental group and the control group (P<0.05).The RDA analysis showed that pH, transparency(SD)and water temperature(WT)were identified as the main factors affecting the changes in phytoplankton community.

Abstract:Construction of a stable and efficient multi-nutrient-level landscape ecosystem is a hotspot of the aquarium industry these years. In order to explore the changes in the structure and stability of the microcosmic ecosystem after the introduction of macroalgae in aquariums, water quality indicators, bacteria and plankton community structure analysis were carried out in different treatment groups. The results showed that: The rising trend of DO and pH in the algae group was higher than those of the non-algae group, and the content of NO₂^--N could be kept at a low level. The content of PO₄^3--P and NH₄⁺-N was significantly lower than those of the non-algae group (P<0.05). The bacterial diversity and evenness index of the algae-group were significantly lower than those of the non-algae group (P<0.05); the plankton community evenness index was highly different among three groups (P<0.05). Bacterial community structure analysis results showed that the first and second dominant bacteria phyla of the non-algae groups and algae-groups were Proteobacteria and Actinobacteria. The abiotic control-groups were Proteobacteria and Firmicutes. The first dominant phylum of plankton communities in each treatment group was Bacillariophyta, accounting for at least 40% of the abundance of plankton communities in the sample. The first dominant genus is Melosira. CCA results showed that the abundance of dominant species in the non-algae group had a positive correlation with the nutrient content and was negatively associated with DO and pH while the algae-group was the opposite. The results indicate that the microcosmic system plankton and bacterial community composition of different nutritional levels are different. Cultivating Caulerpa sertularioides can effectively improve water quality of the ecological aquarium and affect the microcosmic structure, which helps to bulid a stable and efficient landscape ecosystem.

Abstract:From July 2020 to August 2020, 50 stations were set up in the northern Beibu Gulf to investigate bacterioplankton and environmental factors. Spatial distribution of bacterioplankton and the correlation between bacterioplankton abundance and environmental factors were also analyzed.The bacterioplankton abundance in surface layer ranged from 0.33×10⁵ cells/mL to 91.47×10⁵ cells/mL, with an average of 12.61×10⁵ cells/mL; the abundance in middle layer ranged from 0.22×10⁵ cells/mL to 7.48×10⁵ cells/mL, with an average of 2.15×10⁵ cells/mL; the abundance in bottom layer ranged from 1.76×10⁵ cells/mL to 71.33×10⁵ cells/mL, with an average of 17.74×10⁵ cells/mL.The bacterioplankton abundance in the horizontal direction showed a decreasing trend from coastal areas to deep sea areas.There was no significant correlation between the bacterioplankton abundance and the depth in the vertical direction(P>0.05). There was no obvious vertical trend in the bacterioplankton abundance in the coastal waters, but the abundance in surface layer and middle layer and in the offshore water was close, and the abundance in bottom layer was higher than that in surface layer and middle layer. Pearson correlation analysis showed that: the abundance in surface layer had significantly negative correlations with salinity and pH ( P<0.05), and had very significantly positive correlations with nitrate, nitrite and silicate (P<0.01); the abundance in middle layer had very significantly positive correlations with temperature and phosphate (P<0.01), and had significantly positive correlations with nitrate (P<0.05); the abundance in bottom layer had significantly negative correlation with ammonium (P<0.05). This indicated that the spatial distribution of bacterioplankton was affected by multiple environmental factors such as temperature, salinity, pH and nutrients.

Abstract:Potassium persulfate ultraviolet spectrophotometer was used to determine the total phosphorus(TP) and the phosphorus form was extracted by the SMT(Standard Measurement Test) method in the sediments of northern Hangzhou Bay, the organic P (OP) content was the difference between TP and inorganic phosphorus(IP) content, and the spatial distribution of phosphorus forms was also studied. The results showed: TP in the sediments ranged from 722.25 μg/g to 874.49 μg/g which increased gradually along the coast, 63% of TP was IP, and Calcium-bound phosphorus(Ca-P), Organic phosphorus(OP), Fe-Al-bound(Fe/Al-P) phosphorus and Exchangeable phosphorus(Ex-P) were the main forms of phosphorus.The content of Ca-P decreased from south to north in northern Hangzhou Bay, while the content of Fe/Al-P was higher in northern Hangzhou Bay and decreased gradually as it extended to the open sea; The spatial distribution of Ex-P was similar to that of Fe/Al-P which decreased with the distance from the coast.The spatial distribution of OP had no obvious rule in direction from the coast to the open sea which was opposite to that of IP. Bio-available phosphorus(BAP) accounted for 42.22%-56.99% of TP that was higher and would be released under suitable conditions, then used by aquatic organisms. Based on the results,phosphorus had a certain release risk in northern Hangzhou Bay, so it was necessary to formulate corresponding measures to prevent in the ecological environment management.

Abstract:The effects of potassium monopersulfate (PMS) on water environment index and bacterial community were analyzed by water quality physical and chemical factors monitor, culturable bacteria detection in shrimp hepatopancreas and water, and bacterial community analysis. The results showed that:compared with the control, the application of 0.2 g/L PMS could also improve the low content of ammonia nitrogen (NH₄-N) in shrimp culture water. There was no significant difference in water temperature, dissolved oxygen, pH, salinity and nitrite (NO₂-N) after spraying PMS for 24 h and 72 h.The number of culturable bacteria and Vibrio spp. in hepatopancreas decreased from 3.13×10⁶ CFU/g and 1.98×10⁶ CFU/g to 4.30×10⁵ CFU/g and 1.09×10⁵ CFU/g respectively, and the proportion of Vibrio spp. decreased from 63.36% to 25.35%. The number of culturable bacteria and Vibrio spp. in water decreased from 2.70×10⁴ CFU/mL and 6.00×10³ CFU/mL to 8.50×10³ CFU/mL and 1.20×10³ CFU/mL respectively, and the proportion of Vibrio spp. decreased from 22.22% to 14.11%. PMS could significantly reduce the number of culturable bacterias and the proportion of Vibrios spp. in hepatopancreas and pond water. Bacterial community analysis of the water showed that Actinobacteria, Bacteroidota, Cyanobacteria and Proteobacteria were the main dominant phyla. The relative abundance of Nitriliruptoraceae,PeM15,DS001,Llumatobacteraceae,Microbacteriaceae and Rhodobacteraceae was significantly increased after PMS sprayed (P<0.05) (PB1/PA1), and the relative abundances of Barnulmaceae,Saprospiraceae and Stappiaceae were significantly decreased (P<0.05). Compared with the variation trends of 3 days before and after PMS interference, the difference of bacterial community structure between PMS free groups was gradually increased, and reflected that the PMS has better stability in maintaining the bacterial structure of the aquaculture pond. The results may provide data support for the prevention roles and scientific application of PMS in aquaculture.

Abstract:In order to explore the changes of serum energy indexes of Coilia nasus during spawning migration, 49 serum samples of Coilia nasus were collected from Chongming, Zhenjiang and Anqing sections of the Yangtze River from April 15 to June 5, 2019. The results illustrated that: there was no significant difference in the contents of serum glucose, total cholesterol and low-density lipoprotein during the migration from Chongming to Anqing(P>0.05). No significant differences in the contents of serum total protein, triglyceride, high density lipoprotein and free fatty acid were observed from Zhenjiang to Anqing (P>0.05). The significant differences were mainly concentrated in Chongming to Zhenjiang, in which the contents of total protein and triglyceride showed a significant downward trend, decreased by 19.36% and 29.29% respectively; while the contents of high-density lipoprotein and free fatty acid showed a significant upward trend (P<0.05), increased by 60.38% and 23.65% respectively. Among the Coilia nasus samples from different stages of ovarian development in Anqing section, the triglyceride contents of stage IV samples was significantly different from that of stage II and stage III samples (P<0.05), increased by 67.24% and 53.75% respectively, and other indexes had no significant difference among the samples from different stages (P> 0.05).In summary, from Chongming to Zhenjiang, the serum triglyceride, high density lipoprotein and free fatty acid of Coilia nasus showed significant changes (P<0.05), which indicated that the lipid metabolism of Coilia nasus was active in the early stage of migration, and fat should be the main energy source for its migration and development.From Zhenjiang to Anqing, the metabolic level gradually adapted to the energy requirements of migration and gonadal development, so the serum energy index of Coilia nasus tended to be stable in the later stage of migration.

Abstract:Walleye pollock (Gadus chalcogrammus) is the most important commercial fish species in the waters through the Bering Sea to the North Pacific Ocean, and is the keystone species in the ecosystem of this region. Anisakis sp. is the common parasite in walleye pollock, particularly in the liver of this species. Therefore, In order to explore infection of Anisakis sp. to liver of walleye pollock and the factors that affect this process, this study analyzed infection of Anisakis sp. to liver of walleye pollock in the western Bering Sea and explained the factors that impact infection of Anisakis sp. to liver of walleye pollock using generalized linear model. The results indicated that the infection intensity was high and reached 93.3%, however, no significant difference could be observed in infection intensity of Anisakis sp. between sexes of host. The infection intensity of Anisakis sp. increased with the increasing of host size and eastern moving of sampling locations, but decreased with the lapse of time in a day. The study provides the scientific information about biology of walleye pollock and Anisakis sp. in the western Bering Sea and provides the basic data for food web structure in the North Pacific Ocean.

Abstract:Pelagic squid jigging fishery is an important component of China's pelagic fishery. For the sustainable and high-quality development of China's pelagic squid jigging fishery, this paper established its social-ecosystem vulnerability index system from three aspects-climate and environment, species, and social economy, based on the theory of vulnerability. The DEMATEL-ISM-MICMAC (Decision-Making Trial and Evaluation Laboratory-Interpretive Structure Modeling-Matriced Impacts Corises-multiplcation Appliance Classement) method was used to analyze the relationship between indicators and the structure of the index system. The results show that: The vulnerability indicators of China's pelagic squid jigging fishery are linked, among which the most important are fishery resources, fishing intensity, scientific and technological investment, and policy and management; All indicators can be divided into five categories according to their roles: related factors, adjustment factors, driving factors, dependence factors and autonomous factors,among which the first three categories should be paid more attention to;Moreover, apart from fishery resources, the vulnerability system can be divided into four levels: essential causes L4, deep causes L3, transition causes L2 and neighbor causes L1. Long-term monitoring of L3 and L4 indicators, attention to L2 and L3 indicators, and targeted adjustment of L1 indicators are effective ways to maintain the long-term healthy development of pelagic squid jigging fishery in China.This study can not only identify the key factors that affect the vulnerability of pelagic squid jigging fishery and provide theoretical guidance for effective management, but also lay a foundation for the empirical assessment of vulnerability.

Abstract:In order to evaluate the order of the summer fishing moratorium in the South China Sea, this study reviewed plenty of literatures to collect the potential effect factors of summer fishing moratorium. The Delphi method was used to screen out indicators in the South China Sea, and the weight value of each evaluation index was analyzed and calculated based on the analytic hierarchy process. The influences of these factors were also verified by surveys. The results showed that 28 out of the 33 evaluation indicators were selected by the Delphi meeting the order evaluation criteria of the summer fishing period in the South China Sea. The results of analytic hierarchy process indicated that the related personnel (A₁,0.345) and the construction of the summer fishing moratorium facilities (A₃,0.370) of the first-level index weight were more weighted, while the law enforcement facilities (B₆,0.200) and fishermen (B₁,0.193) had larger weights among the second-level indicators. Among the three-level indicators, the law enforcement funds (C₁₆,0.100), the law enforcement equipment (C₁₇,0.100), subsidies for fishing moratoriums (C₃,0.087), illegal fishing of vessels without certification (C₂₆,0.072), and the invasion fishing of Vietnamese fishing vessels (C₂₇,0.052) accounted for a larger proportion. The case verification showed that fishery law enforcement funds and law enforcement equipment had key impacts on the current condition of summer fishing closure order in the South China Sea; Fishermen's subsidies during the fishing moratorium, illegal fishing of vessels without certification and the invasion fishing of Vietnamese fishing vessels had a great impact on the order. To some extent, this study revealed the impact of each evaluation index on the summer fishing closure order, which can provide some reference for standardizing the order and improving the summer fishing closure system in the South China Sea.

Abstract:Based on the data collected by saury stick-held operation in the northwest Pacific from July to October in 2016 and from June to October in 2017, we analyzed the factors(fishing operations and marine environment) influencing the stick-held net status of Pacific saury(Cololabis saira) fishery based on boosting regression tree weighted analysis and generalized additive model. The results showed that: Among the factors influencing the maximum net sinking depth, the top four factors with weight are current speed of 30 m layer(20.15%), current speed of 60 m layer(18.92%), length of lead line loose(16.85%) and current speed of 10 m layer(15.52%); The top four influencing factors of lifting speed were hauling speed(23.17%), current speed of 30 m layer(20.05%), current speed of 10 m layer(18.27%) and current speed of 60 m layer(16.26%). Current speed of 30 m and 60 m layers and length of lead line loose had significant effects on the maximum net sinking depth;The maximum net sinking depth was positively correlated with the length of lead line loose, there was a negative correlation between the maximum net sinking depth and current speed of 10 m, 30 m and 60 m layers; hauling speed and current speed of 10 m, 30 m and 60 m layers had significant effects on lifting speed; the lifting speed was positively correlated with the hauling speed; there was a negative correlation between the lifting speed and current water speed. Hauling speed was the most important factor affecting the lifting speed, followed by current speed of 30 m layer, current speed of 10 m layer and current speed of 60 m layer.

Abstract:The West Indian Ocean is an important fishing area in the world. The evaluation of fishery resources utilization is an important basis for scientific management and sustainable development of the resources.According to the FAO’s catch data from 1950 to 2018 and trophic level of fish species in the western Indian Ocean, the mean trophic level (MTL) of 69 years and fishing in the balance index (FiB) were analyzed to evaluate the development and utilization of fishery resources.The results showed that the catch showed an increasing trend from 1950 to 2018 in the western Indian Ocean, and the increasing trend could be divided into three stages including 1950-1982, 1983-2005 and 2006-2018. The catch of small sardines was the highest in the species from the western Indian Ocean.The MTL of the catch decreased first, then increased, and then stabilized during 1950 to 2018.According to the above three phases, its average MTL were 3.49±0.14, 3.71±0.06 and 3.71±0.03 respectively, and the high MTL of the catches (TL>3.25) were 4.04±0.04, 4.09±0.04 and 4.13±0.01 respectively.It is found that the average trophic level fromthe high MTL (TL>3.25)catch and total catch show the similar changing trend (P<0.001).The FiB index showed an upward trend on the whole, and the mean FiB of three stages were 0.099 8±0.165 9, 0.804 1±0.184 9 and 0.978 2±0.067 0 respectively.According to the analysis, the early catch was relatively low in the western Indian Ocean from 1950 to 1982, and the MTL and FiB showed a fluctuating decreasing trend with the increase of the catch of low trophic level such as sardines.From 1983 to 2005, with the increase of high trophic level catch, MTL and FiB showed a gradually increasing trend.From 2006 to 2018, MTL and FIB were relatively stable at a high value.The results show that the fishery resources in the western Indian Ocean are in good condition, the ecosystem structure and function are stable, and the resources of western Indian Ocean still have great development potential.

Abstract:By incorporating the sea surface temperature (SST), chlorophyll-a mass concentration (Chl.a), sea surface height anomaly (SSHA), ocean mass and geostrophic current from multi-source remote sensing observations, this paper models and predicts the temporal-spatial distributions of the catch per unit effort (CPUE) of O. bartramii in the northwest Pacific Ocean with the supervised learning algorithm-based back propagation (BP) neural network model. The multi-source remote sensing data were used to build the BP neural network model, and the accuracy of the model-simulated and -predicted O. bartramii CPUE was then evaluated with the historical fishery data during 2004 to 2017 in the northwest Pacific Ocean from the Chinese Squid-Jigging Technology Group of Shanghai Ocean University. Compared with the traditional scheme of predicting the spatial-temporal distributions of O. bartramii CPUE with SST, Chl.a and SSHA only, the accuracy of model-simulated and -predicted CPUE can be further improved after incorporating the ocean mass and geostrophic current into the BP neural network model.Specifically, the standard deviation (STD) and root mean square error (RMSE) of model-simulated O. bartramii CPUE both increased by 22%, and STD of model-predicted O. bartramii CPUE increased by 31% and RMSE decreased by 26%.

Abstract:Understanding and mastering the environmental factors that affect the resource abundance of the winter-spawning cohort of Todarodes pacificus are of great significance to the development of fishery forecasts and fishery resource assessment and management.In this study, Sea Surface Temperature (SST) was used to measure the catch per unit effort (CPUE) of the winter-spawning cohort of Todarodes pacificus from 1998 to 2018, the spawning ground (25°N-40°N and 125°E-145°E) during the spawning period from January to March, and the feeding ground (26°N- 40°N and 125°E-145°E) during the feeding period from June to July,the SST value affecting CPUE was obtained by generalized linear model analysis, and we made the spatial overlay analysis of the CPUE and the obtained influence factor SST in consecutive high-value years (2007, 2008, 2009) and consecutive low-value years (2016, 2017, 2018).The results showed that CPUE and spawning ground SST from January to March were significantly related to January (25°N-40°N and 125°E-144.5°E),and the optimal range of SST in this sea area was 18-26 ℃. The significant correlation between CPUE and SST in June and July was mainly concentrated in July (27°N-39.5° N and 125°E-144.5°E), and the optimal range of SST in this sea area was 18-28 ℃,the SST of consecutive high value CPUE years was lower than that of consecutive low value years. The study suggests that the stock abundance of the winter-spawning cohort of Todarodes pacificus was significantly affected by SST.

Abstract:Scientific and reasonable enterprise spatial layout is conducive to recreational fishery business units to reduce resource allocation costs and give full play to regional advantages. Taking 799 recreational fishery business units in Hainan province as the research object, the spatial distribution characteristics of recreational fishery business units in Hainan province were analyzed from the three dimensions of distribution form, distribution equilibrium degree and distribution density by nearest neighbor index, coefficient of variation and kernel density analysis, and the influencing factors of spatial distribution were explored using clustering and outlier analysis and vector data buffer method. The results showed that: the distribution pattern of recreational fishery business units in Hainan province is agglomeration type, and the order of agglomeration degree from high to low is Qiongbei district, Qiongnan district, Qiongxi District, Qiongdong district and Qiongzhong district. the spatial distribution density of the recreational fishery business units showed significant differences, forming the density characteristics of north and south poles, sporadic agglomeration and coastal surrounding inland; the density gradient presented four grades of decreasing difference from coastal to inland. the spatial distribution of recreational fishery business units in Hainan province was largely affected by resources of transport, market and tourist, which were mainly located near the scenic spots, around the cities and along the traffic trunk roads. Furthermore, the population size and economic level also partly affected the spatial distribution of recreational fishery business units. The research results can provide a scientific basis for optimizing the location selection and improving the operation efficiency of recreational fishery business units in Hainan province.

Abstract:In order to further improve the quality of crude large yellow croaker liver oil and remove undesirable flavors, develop high-quality large yellow croaker liver oil products, in this study, four processes were used to refine the crude oil extraction of large yellow croaker liver (degumming, deacidification, decolorization, distillation and deodorizing) and different deodorization methods (distillation, solid phase adsorption, deodorizing liquid, green tea polyphenols). After treatment, the physical and chemical properties, fatty acids, sensory and volatile flavor components were comprehensively analyzed. The results showed that the acid value of refined large yellow croaker liver oil was reduced by 63.50% compared with crude oil, the iodine value was increased by 1.19 times, and the peroxide value was reduced by 39.02%. The relative content of fatty acids displayed a significant optimization effect. The saturated fatty acids of large yellow croaker liver oil increased by 1.20 times, the polyunsaturated fatty acids increased by 1.71 times, and the content of EPA and DHA increased by 1.84 times. The six deodorization methods can significantly reduce the oily, fishy and sour tastes, and the fatty acid composition and content are slightly different, but the overall quality is relatively high, and their nutritional content and functional characteristics can be guaranteed. The deodorizing effect of GTP is better, it has no effect on the acid value, the iodine value is increased by 1.12 times, the peroxide value is reduced by 37.8%, and the content of unsaturated fatty acids is increased. Among them, the contents of EPA and DHA doubled compared with crude oil. Aldehydes such as 2,4-heptadienal and 2,4-decadienal were reduced by 31.25% and 56.88%, and 3,5-octadienone was removed as much as 81.84%, 1-octene-3 -Alcohol was reduced by 52.76%, and grassy hexanal and nonanal were added, which effectively removed the oily and fishy odor, produced a pleasant fragrance, and greatly improves the flavor of large yellow croaker liver oil. This research provides a theoretical basis for the development of large yellow croaker liver oil and the production technology of liver oil rich in high unsaturated fatty acids and good flavor and high quality.

Abstract:The best biological enzyme was selected according to the inhibition rate of α-glucosidase. Based on the single factor, optimization of enzymatic hydrolysis conditions could be obtained through the response surface. The enzymatic hydrolysate of the defatted antarctic krill powder was separated and purified by ultrafiltration and G-25. The molecular mass and distribution of enzymatic hydrolysate and peptides were studied by gel chromatography. The results showed that: The compound protease had the best enzymatic hydrolysis effect; The best enzymolysis conditions were enzymolysis time 5.9 h, material-liquid ratio 3.75∶1, enzyme addition amount 0.062 g/g(raw material); The molecular mass of the enzymatic hydrolysate was concentrated below 3 000 u, accounting for 98.63%; The C4 (<3 ku) component by ultrafiltration had the best inhibition rate of α-glucosidase [IC₅₀ was (14.89±2.15) mg/mL]; After purification by G-25, the C4-2 fractions (<3 ku) had higher α-glucosidase inhibitory than other fractions[IC₅₀ was (4.64±0.14) mg/mL]; In the C4-2 fraction, 97.6% of peptides were <1 000 u. The molecular weights of C4-2-1, C4-2-2, and C4-2-3 were 597 u, 335 u, and 246 u respectively. This research for the first time studied the method of preparing α-glucosidase inhibitory active peptide from Antarctic krill powder, which provides a basis for the comprehensive utilization of Antarctic krill resources.

Abstract:In order to investigate the dielectric properties of the different amino acid solutions during microwave heating, the 10 kinds of amino acid solutions [glycine (Gly), proline (Pro), cysteine (Cys), glutamine (Gln), lysine (Lys), methionine (Met), histidine (His), arginine (Arg), tyrosine (Tyr) and tryptophan (Trp)] were determined by network analyzer and coaxial probe technology. These solutions were heated for (0, 1, 3, 5 min) using microwave irradiation (250 W). Except for Tyr, the dielectric constant of other amino acid solutions gradually decreased with the increasing of frequency at the frequency of 0.3~3 GHz. During microwave heating, the dielectric loss of Arg and Lys solutions tended to decrease with increasing frequency, while other amino acid solutions (except Gln) tended to increase. During the microwave heating process, the dielectric loss of Gln solution displayed an obvious turning point at 0.9 GHz (especially under microwave heated for 3 min and 5 min), which showed a trend of decreasing first and then increasing. The penetration at 915 MHz was higher than 2 450 MHz. When heating for 3 min, the maximum penetration depth of Tyr solution at 915 MHz was (180±0.12) mm, and the maximum penetration depth of Trp solution at 2 450 MHz was (20±1.5) mm. The pH of Arg, Lys solutions decreased due to ionizing during microwave heating. The molecular weight and isoelectric point of amino acids affect the penetration depth of heterocycle amino acid and aliphatic amino acid solutions, and the correlation between the penetration depth of amino acid solution and the molecular weight of amino acid (R²>0.90) was higher than its isoelectric point (R²>0.82). With the increase of heating time, the critical frequencies of heterocyclic amino acids (Tyr, His, Trp, Pro) solutions decreased, whereas the critical frequencies of aliphatic amino acids (Met, Lys, Arg, Gly, Gln, Cys) solutions increased (P<0.05).

Abstract:This study screened out the natural products that have synergistic antibacterial effects on strain Klebsiella pneumoniae when combined with antibiotics. The K-B method was used to determine the drug resistance of strain K. pneumoniae to eight types of antibiotics. The broth dilution method was used to determine minimal inhibitory concentrations (MICs) of antibiotics and three types of natural products. Checkerboard method was used to determine the synergistic antibacterial activities of antibiotics in combination with anthocyanins or caffeic acid against strain K. pneumoniae. The synergistic bacteriostatic effect of the combination of caffeic acid (CA) and antibiotics was evaluated by time-dependent killing curve. The results showed that: The strain K. pneumoniae was resistant to eight types of antibiotics, and completely resistant to sulfamethoxazole (SMZ), clindamycin, chloramphenicol (CHL) and tetracycline; The MICs of antibiotics ranged from 16 μg/mL to >512 μg/mL; The MICs of anthocyanins and CA were 25 μg/mL and 1 875 μg/mL respectively, which exhibited great antibacterial activities on strain K. pneumoniae, and the MIC of cinnamaldehyde was >250 μg/mL, which had no antibacterial effect against strain K. pneumoniae, and anthocyanins enhanced the susceptibility of strain K. pneumoniae to ceftazidime and CHL by reducing 4-fold of the MICs of two antibiotics; CA synergistically enhanced strain K. pneumoniae susceptibility to 8 kinds of antibiotics, and the MICs of antibiotics decreased by 8~>4 096 times; It is obvious that the synergistic effect of the combination of caffeic acid with antibiotics is better than that of anthocyanins in combination with antibiotics, and furthermore, CA in combination with SMZ or CHL could inhibit bacteria for at least 24 h. This study for the first time reported that the combination of CA with antibiotics had a significant synergistic antibacterial effect on multidrug resistant strain K. pneumoniae, and showed that combination therapy was an effective strategy to reduce the drug resistance of pathogens.

Abstract:The effects of changes in microbial communities and microbial decomposition of particulate organic matter (POM) during simulated sinking and incubation were inverstigated under progressively increased hydrostatic pressure. DNA-stable isotope probing (SIP) and high-throughput sequencing of 16S rRNA genes showed that 19 OTUs were labelled by ¹³C, and were affiliated mostly with Bacteroidia, α- and γ- Proteobacteria in situ water. The types and abundances of active OTUs in PA or FL faction differ significantly under several pressure gradients. The results revealed the clear compositional differences between the active PAM and FLM communities. Dynamic succession between PAM and FLM occurred with increasing hydrostatic pressure. Microbial network interactions changed dramatically with pressure, dominated by positive interactions at low pressures (0.1, 10 and 30 MPa) and by negative interactions at high pressure (60 MPa), suggesting strong species competition in the deep ocean. The results further showed that microbial communities exhibited clear separation and compartmentalization at high pressure, indicating network resilience and stability. The results significantly expanded the understanding of how pressure during simulated sedimentation affects the community structure and function of microbes associated with the descending particulates in the ocean.