Abstract:The taxonomic status of “silver beachhead” in Tribolodon migratory population in Suifen River has always been controversial. In this study, we used DNA barcoding COⅠ and gene markers(fst and mitfa) to identify 115 individuals from Suifen River, including Tribolodon hakonensis (40),T. brandtii(38) and “silver beachhead”(34), and 3 individuals of T. hakonensis from Lake Osorezan, Japan. The results of mitochondrial COⅠgene amplification showed that a total of 11 haplotypes were obtained,of which 5 haplotypes were exclusive to T. hakonensis, 5 haplotypes were exclusive to T. brandtii, and 1 haplotype (hap6) was exclusively shared by Japanese population of T. hakonensis,“silver beachhead” population shared 1 haplotype with T. hakonensis, and shared 3 haplotypes with T. brandtii.Cluster analysis did not support the “silver beachhead” population as an independent species.The results of amplification of two gene markers showed that “silver beachhead” population had both genotypes of T. hakonensis and T. brandtii.Combining the above two analysis results,it is found that there are hybrid individuals of T. hakonensis and T. brandtiiin “silver beachhead”.In conclusion, this study confirmed the taxonomic status of the “silver beachhead” population, that is, “silver beachhead” is a mixed population composed of T. hakonensis, T. brandtii and their hybrids.The results of this study provide a scientific basis for the classification, conservation of germplasm resources and wild release and enhancement of Tribolodon.

Abstract:Mastering the distribution of species composition and their abundance of fishes is basic for the conservation and management of fish diversity. Based on the data collected from Chuhe River in December 2015 and May 2016, we examined how the fish assemblages vary spatially and seasonally in this study area. A total of 4 798 individuals representing 45 species were collected, a total of 45 fish species belonging to 37 genera, 13 families, and 6 orders were collected during the investigation, with cyprinids accounting for 55.56% of the collected species. One-way ANOVA indicated that there were no significant seasonal differences in fish diversity,however, notable differences in fish diversity were observed among sampling sites. Carassius auratus, Cyprinus carpio, Abbottina rivularis, Pseudobagrus fulvidraco, and Pseudobrama simoni, were the dominant species. Omnivorous and detritivore fish species were the most frequent of the four feeding functional groups, which account for 63.04% of the total, and sedentary fish species (89.13%) were the most frequent of the three ecological groups, whereas demersal fishes (45.65%) were the most frequent of the three habitat types. Large commercial fishes account for a very small percentage of the whole fishes and the relative importance index (IRI) value is low. Analysis of species richness and diversity indicated that the fish diversity of the downstream of Chuhe River was low, with great spatial variation. The species richness and diversity of the upstream of Chuhe River was high, while the fish species in Qinliu River and Lai'an River take the second place. Fish species were similar between two seasons, and fish assemblage structures showed no significant difference between seasons. Variations among different reaches were observed for both fish species diversity and assemblage structures. Generally, the downstream of the river had relatively lower species diversity, while those in the upstream were relatively higher. Obviously fish community overlaps, hardly any separation were observed between seasons, when the spatial variations in fish assemblages among sections were considered, fish assemblage structures, not species diversity, showed significantly variation. Fish assemblage structures variation were mainly due to the spatial distribution of some dominant fishes, such as Carassius auratus, Cyprinus carpio, Abbottina rivularis and Pseudobagrus fulvidraco.

Abstract:In this study, we determined the mitochondrial DNA cytochrome b gene (Cytb) sequences of the northern, equatorial and southern populations of Sthenoteuthis oualaniensis in the Eastern Indian Ocean, and analyzed the phylogenetic relationship.It was shown that S. oualaniensis in the Eastern Indian Ocean had an overall high haplotype diversity of 0.939 and a high nucleotide diversity of 0.015.F_st value among three populations was 0.661 (P<0.01), reaching a high level of interpopulation genetic differentiation with significant genetic structure. Two lineages were revealed in three S. oualaniensis populations in the Eastern Indian Ocean. Lineage 1(the northern lineage of the Eastern Indian Ocean) is dominated by individuals from the northern population of the Eastern Indian Ocean; lineage 2(the southern lineage of the Eastern Indian Ocean)mainly consists of individuals from the equatorial population and the southern population of the Eastern Indian Ocean,and lineage 2 underwent population expansion. The great north-south hydro-logical difference in the Eastern Indian Ocean may be the reason for the north-south lineage divergence of S. oualaniensis in the Eastern Indian Ocean. The differences and characteristics of the north-south lineages should be considered in the utilization and management of S. oualaniensis resources in the Eastern Indian Ocean.

Abstract:A 30-day feeding experiment was conducted to investigate the effects of dietary lipid (mass fraction is 7%, 10%, 14%, and 17%) on the gonadal development, fatty acid composition, and tissue structure of Argopecten irradias. Four isonitrogen (mass fraction is 47% crude protein) feeds were formulated with the supplementation of graded levels of fish oil (mass fraction is 0%, 3%, 6%, and 9%). The scallops fed Nitzschia closterium f. minutissima served as control group. The scallops [initial body mass:(40.79±1.70 g)] were stocked in glass reinforced plastic tank (1 000 L), and each diet was randomly allocated to three groups of scallops. (Result) Mortality rate was not significantly affected by dietary lipid, but mortality rate of control group was significantly lower than feed treatment (P< 0.05). The gonadosomatic index (GSI) showed an increased tendency first and then decreased with the increase of dietary lipid. The highest GSI was observed in scallops fed F14 diet, with no significant difference from control group (P> 0.05), significantly higher than the initial period (P<0.05). The highest moisture content of female gonad was observed in scallops fed F10 diet, significantly higher than that fed F17 diet (P< 0.05). The lipid content of female gonad was significantly higher than male gonad (P< 0.05). The SFA, MUFA, n-3PUFA, DHA, and EPA contents were significantly affected by dietary lipid (P< 0.05), and the highest content was observed in F14 or F17. The gonadal tissue sections showed that the follicular cavity was filled with oocytes and seminocytes. It was feasible to partially replace unicellular algae with formulated feed and the gonad could be developed to the requirement of seedling. These results above suggest that the optimal dietary lipid level for Argopecten irradias is about 14%.

Abstract:Small yellow croaker (Larimichthys polyactis) is an important economic species and the dominant species in China’s coastal waters,playing a key role in the structure of food web. The contents of muscle fatty acids from 58 small yellow croakers were determined by gas chromatography-mass spectrometer and the characteristics of their changes in composition were analyzed. The feeding habits of yellow croaker were investigated based on the role of fatty acids as dietary tracers. The results showed that 30 kinds of fatty acids were detected in the muscle of small yellow croaker, with prevalent fatty acids C16∶0, C17∶0, C18∶1n9c, C18∶3n3,C16∶1n7,C20∶1, C20∶4n6, C20∶5n3 (EPA), C22∶6n3 (DHA), among which the C16∶0 accounted for 23.12%, C18∶1n9c for 16.67%, C16∶1n7 for 11.45% and C22∶6n3 for 11.40%. The average content of unsaturated fatty acid (UFA) in muscle reached 60.20%, which was significantly higher than that of saturated fatty acid (SFA, 39.80%), and the proportion of DHA and EPA in muscle accounted for 15.54%, indicating that the fish had higher nutritional value. Two-way ANOVA showed that there was a significant difference in saturated fatty acid SFA among body length groups, and the content decreased with the increase of body length (P<0.05), while the content of monounsaturated fatty acid MUFA had significant seasonal differences (P<0.05). Most of the characteristic fatty acids had no significant difference among body length groups in each season(P>0.05), while the contents of C16∶1n7, C20∶1 and C18∶1n9c in 120-139 mm body length group and > 180 mm body length group in winter were significantly lower than those in other seasons.The fatty acid signatures, known as trophic markers, revealed that small yellow croaker was a kind of fish that feeds on plankton, benthic and swimming animals, particularly on diatoms, dinoflagellates, zooplankton and benthic organisms. This highlights the fatty acid markers to indicate the food source of small yellow croaker, supporting and verifying the results of contents of stomach analysis in the literature, and also provides an important reference for the study of feeding ecology of small yellow croaker.

Abstract:In order to study the pollution level and source of polycyclic aromatic hydrocarbons (PAHs) in the breeding environment of Macrobrachium rosenbergii in Jinshan district of Shanghai and to assess the food health risk, 16 kinds of optimal PAHs were detected by HPLC. The results showed that: In the cultivation area, the total PAHs content and the settling flux in the dry and wet deposition were 5.52-9.45 μg/g, 47.99-100.42 ng/L and 3.75-6.42 μg/m²·d, 83.32-174.36 ng/m²·d, respectively. In the dry deposition, the high ring was dominated, while in the wet deposition, the low ring was dominant. The total PAHs content in the water is 342.76-1 520.83 ng/L, which is mainly dominanted by low ring. Compared with other breeding areas in China, PAHs pollution in the water of research areas is at a medium level; the content of PAHs in soil and sediment was 1 000.45-2 138.46 ng/g and 1 763.70-3 656.97 ng/g, respectively. The content of PAHs in high ring was much higher than that in low ring, which was also higher than that in other aquaculture areas. The total PAHs contents in zooplankton and phytoplankton was 46.18-134.63 μg/g and 26.13-145.39 μg/g, respectively, which were dominated by 4-ring PAHs; The average total PAHs content in the three growth stages of Macrobrachium rosenbergii was 63.09 ng/g (Seeding stage), 111.89 ng/g(Growth stage) and 148.77 ng/g(Incubation stage), respectively, showing the existence of bioenrichment phenomenon. The PAHs content in the 3 and 4 cyclic PAHs in the shrimp meat was relatively high. Compared with aquatic products in other breeding areas, PAHs in the study area in Macrobrachium rosenbergii were at a lower level. The ratio method and principal component analysis method were used to analyze the pollution sources. The results showed that the air settlement in the breeding area coexisted with many pollution sources, and the pollution sources in the wet settlement were mainly petroleum sources. The main source of pollution in dry deposition was coal and wood combustion. The main pollution sources of water bodies were petroleum sources; the main source of coal combustion was in the soil. The pollution sources in sediments were similar to those in soil, mainly coal combustion and incomplete combustion of fossil fuels. The results of risk assessment showed that the lifetime cancer risk of Macrobrachium rosenbergii was 1.89×10^-8-1.37×10^-6, which was within the acceptable range and would not harm human health under normal eating conditions.

Abstract:It is very important to monitor and protect the water environment and biological resources in Baiyangdian Lake because of Xiong’an New Area. In order to investigate the spatial and temporal variation characteristics of the community structure of Cladocera and Copepods and their relationship with water environmental factors in Baiyangdian Lake, canonical correlation analysis (CCA) was used to analyze the abundance, diversity index and aquatic environmental factors of Cladocera and Copepods in Baiyangdian measured in May, August and October 2019. Based on the technology of DNA barcoding, 26 species of Cladocera and Copepods were identified belonging to 8 families, 17 genera. The dominant species are Bosmina coregoni, Thermocyclops hvalinus and Ectocyclops phaleratus throughout the year 2019. The spatial and temporal characteristics of abundance and diversity index are different. The main expression is that the variation of regional distribution is greater than the seasonal variation, and it is greater in the southern region than in the northern region in space. Analysis of correlation between Cladocera and Copepods community structure and water environment, the results showed that temperature, transparency, nutrients and other environmental factors affected the growth, development, feeding and other activities of Cladocera and Copepods as the main environmental factors affecting their abundance and community structure characteristics. S, Pb and Zn are the key influencing factors, which have significant negative effects on Cladocera and Copepods. Therefore, the long-term ecological environment monitoring and species research in Baiyangdian Lake will provide reference for the implementation of water conservancy projects and construction of Xiong’an New Area.

Abstract:In the study, constructed wetlands with 3 plant species (Canna indica, Acourus calamus and Luthrum salicaria) were respectively built to obtain the optimal treatment conditions. In the treatment experiments, various factors were respectively arranged as follows: C/N/P (50/10/1, 25/5/1, 25/5/2, and 25/5/3), salinity (0.5, 1 and 2), and the HRT (1, 2, 3 and 4 d). The removal rate of TN, TP and COD in constructed wetland, the content of NH₃-N, NO₃-N, NO₂-N and PO₄^3- in influent and growth parameters of three plants were determined. The results showed that:When the HRT=4 d, the influent salinity of 1.0 and C/N/P was 25/5/2 (COD=50 mg/L, TN=5 mg/L, TP=4 mg/L), the highest removal rates of TN (90%), TP (97%) and COD (65%) were reached;Among the different plant and substrate combinations, the Canna indica wetland device had the best removal effect, the chlorophyll (SPAD value) and superoxide dismutase in Canna indica were relatively high, and the content of malondialdehyde is lower, respectively, 40.6, 1 212 U/g and 2.45 nmol/g, and the amino acid content was 1.82%;With influent salinity of 1 and C/N/P(25/5/2), the microbial community structure in the constructed wetland was optimized, and the dominant flora was Proteobacteria, which is a common functional flora in wastewater treatment. Therefore, Canna-constructed wetlands can treat low-salinity aquaculture wastewater, strengthen the treatment effect of constructed wetlands, improve the synergistic decontamination and salinity tolerance of plants-microorganisms, and provide technical support for coastal water body restoration.

Abstract:In order to explore the suitable growth conditions and chlorophyll fluorescence parameters of two red algae Prorocentrum donghaiense and Skeletonema costatum,temperature(17,20,23,26 ℃) and light (40,80,120,160 μmol photons/(m²·s)),phosphate (0.1,1.0,5.0,10.0 μmol/L),initial biomass(1×10⁴,3×10⁴,5×10⁴,7×10⁴ cells/mL) , the algae culture experiment of the 4 factors with 4 levels was carried out. The results showed that the phosphate concentration (P<0.01) had the most significant effect on the peak chlorophyll a concentration of the two algae. And it was not significantly affected by light, temperature, and initial biomass. Phosphate addition experiment showed that in the low phosphate environment of 0.1 μmol/L and 1.0 μmol/L, the biomass and its stability of Prorocentrum donghaiense were higher than that of Skeletonema costatum. Prorocentrum donghaiense can survive after the high initial biomass depleting the phosphate, while the cell abundance of Skeletonema costatum declined continuously. In the environment of 5.0 and 10.0 μmol/L high phosphate, Skeletonema costatum proliferated faster and with higher biomass than Prorocentrum donghaiense.The fluorescence parameters F_v/F_m and α of Prorocentrum donghaiense were more stable than those of Skeletonema costatum, which showed the photosynthetic activity of Prorocentrum donghaiense was also stable.The smaller cell volume and larger specific surface area made Skeletonema costatum reach the peak value of biomass rapidly in the early stage of culture, which indicates that it has strong phosphate utilization ability. In the 10.0 μmol/L phosphate group, the four fluorescence parameters were the largest and the photosynthetic activity was the strongest, so it is necessary to prevent and control eutrophication.The photosynthetic activity of Prorocentrum donghaiense was more affected by light, and the photosynthetic activity of Skeletonema costatum was more affected by phosphate and light.

Abstract:Marine environmental pollution incidents, which happened frequently in recent year, have done great damage to marine environment. It is of great significance to establish a sound early warning mechanism for effectively avoiding the occurrence of marine environmental pollution incidents or reducing their destructiveness. However, the present conditions, such as the weakness of the early warning principle and system related provisions that embedded in legal documents, the difficulty of early warning coordination resulted from the classification system of marine environment management, the deficient information system arising from monitoring technology, facilities construction, and information sharing, affect the effectiveness of early warning management. Based on the experiences of the foreign countries in marine environmental early warning, policy recommendations can be provided as follows: Early warning principles and systems should be fully embedded in legal documents of marine environmental protection; The comprehensive coordination mechanism of early warning should be improved; An efficient application platform of early warning system for marine environment should be constructed.

Abstract:The illuminance distribution calculation and simulation of fishing lamps is the crucial means to arrange the lighting of fishing boats reasonably. With the assistance of wind speed, relative humidity, parameters of the fishing lamps and fishing boats and the analysis of photon transmission characteristic, a sea surface illuminance model of the fishing lamps for the lighting of fishing boats has been established through Monte Carlo method. The model adopts the Mie scattering to calculate relative humidity and the absorption and scattering for the wind speed of sea surface to photon and considers the impact for the wind speed of sea surface on the Fresnel coefficient while the photons are entering into the water. The comparison between the model and the superposition method shows that the linear fitting slope coefficient of the theoretical calculation value and the measured value of the model is closer to 1.By calculating the sea surface illuminance at different wind speeds and relative humidity, the results show that: the illuminance first increases and then decreases with the increase of the distance from the ship's midship line; the relative humidity is constant, as the distance from the midship line increases, first the greater the wind speed, the greater the illuminance, and then the greater the wind speed, the lower the illuminance; the wind speed is constant, and the relative humidity has little effect on the sea surface illuminance. The purpose of this research is to establish a sea surface illuminance model for fishing lamps to provide a theoretical basis for future research on lighting configuration.

Abstract:Feeding is one of the primary factors determining efficiency and cost in aquaculture. In order to improve breeding efficiency, a new method of measuring fish feeding intensity based on depth image was proposed in this paper.This method is not limited by lighting conditions of aquaculture farms, and it does not rely on clear water or stable background. Through processing the depth data, the fish target foreground extraction and background image removal are realized with least amount of calculation, and clear fish feeding images are obtained by the depth image technology.The total number of the target pixels in the depth map is used to estimate the number of the feeding fish. Combined with the change rate of the target pixels, the feeding intensity of fish can be evaluated in real time. Compared with the traditional analysis based on two-dimensional image texture features, the method greatly reduces the amount of calculation task and provides an implementable scheme for the real-time measurement in aquaculture.The results show that the near-infrared depth image, which is not limited by the imaging conditions of the feeding site, can effectively represent the feeding behavior of fish.The method has ideal analysis effect for monitoring the fish that eat floating feed on the water surface and inhabit at the bottom of water body in non-feeding stage. This paper provides a new technical means for fish behavior analysis, which has positive guiding significance for the application of precision feeding.

Abstract:According to the catch data of Sthenoteuthis oualaniensis in the northern Indian Ocean during 2017-2019 provided by the Squid Jigging Technology Group of the China Overseas Fisheries Association and the High Seas Seine and Trawl Technology Group, statistical analysis was made based on the above data with the effort, catch and CPUE for each of the three fishing methods of light lift net, light casting net and jigging. Through catch gravity analysis, cluster analysis and two-way analysis of variance, the spatial and temporal distribution of the three fishing methods and their differences in the years were studied and analyzed. The results showed that the annual catch of S. oualaniensis increased gradually, the yield for 2017, 2018 and 2019 were 28 347, 68 535 and 180 094 t, respectively. In terms of annual changes, CPUE fluctuates greatly; and from the monthly changes, the monthly output is consistent with the trend of CPUE changes. The yield center of gravity of each of the three fishing methods shows counterclockwise changes, moving from south to north and from east to west. Through clustering analysis, the lighting lift net can be divided into five categories, the light casting net can be divided into four categories, squid fishing is divided into six categories; main catch was focused in the area of 12.5°N-14.5°N,58°E-60°E and 16°N-18°N,61.5°E-63°E.Based on time and space as the factors, the analysis of the sea area between different longitude shows that CPUE is obviously different at different times and spaces, and there are significant differences in different fishing methods. The study holds that the future research should strengthen the sample collection work of time series, consider the change law and its root causes of environmental factors to analyze the squid fishery, and provide a basis for the subsequent rational development of the fishery and the establishment of relevant fishing forecast model.

Abstract:Trawling activities of recreational fishing boats are part of recreational fishery activities. Fishing gears such as trawls on recreational fishing boats were required by the government to be standardized prior to summer fishing moratorium of 2017. The composition of catches would vary with the change of fishing gear and mesh size, so the standardized transformation of trawl may have a positive effect on fisheries resources and their habitats. To investigate the effects of recreational fishing boat experiential trawl standardized transformation on nekton community structure, bottom trawl surveys on composition of nekton community were conducted in Yueqing Bay. The surveys were conducted in the spring and summer of 2016 before the transformation and the spring and summer of 2017 after the transformation. The difference in average body length of captured nekton samples was tested by T-test. The composition of nekton and the effectiveness of trawl transformation were analyzed by combining some parameters such as index of relative importance, biodiversity index, and species replacement. The results showed that there was difference in species composition of the nekton via the transformation of trawl, with the evident species replacement. Portunus trituberculatus and Larimichthys polyactis were the mutual dominant species in spring through the reconstruction, and the common species were Exopalaemon carincauda. P. trituberculatus, L. polyactis, Harpodon nehereus and Coilia nasus were the mutual dominant species in the summer through the reconstruction. The number of species increased by 22 and decreased by 18, with species replacement rate of 58% among two seasons of spring. During summer, 25 species increased and 29 species decreased, and the replacement rate was 75%. Both replacement rates exceeded 50%. The abundance of nekton reduced but the biomass improved with the standardized transformation. After the transformation of nets, the average abundance of swimming animals in the spring catch decreased from 5.91×10⁴ ind./km² to 2.72×10⁴ ind./km² and the average abundance in summer from 9.76×10⁴ ind./km² reduced to 3.45×10⁴ ind./km². The average biomass increased from 310.87 kg/km² to 356.07 kg/km² in spring, and from 444.90 kg/km² to 515.90 kg/km² in summer. The average body length of several important economic species was significantly larger than that before the transformation.L. polyactis, Lateolabrax japonicus and C. nasus were greatly larger after the transformation; the body length of L. polyactis and the carapace width of P. trituberculatus increased significantly. In addition, the proportion of nekton was still high after the net transformation. In spite of that, the juvenile proportion of some important economic species fell a bit after thetransformation. For instance, as the mutual species among spring, the juvenile proportion of L. japonicus was 100% and 67% before and after the nettransformation, which decreased by 33%. But the proportions of some dominant species such as P. trituberculatus and L. polyactis were still above 90%. The dominance of prey species declined. For example, the Gobiidae's index of relative importance decreased markedly. The standardized transformation of experiential trawl nets of recreational fishing boats had some protective effect on juvenile of important economic species. This measure was conducive to the sustainable development of fishery resources and the protection of habitats in Yueqing Bay, which promoted the development of recreational fishery to a certain extent. However, in order to protect fishery resources and habitats, the proportion of juvenile in catches still needs to be reduced.At present, the fishing activities of recreational fishing boats in China are not restricted by the system of summer fishing moratorium. Furthermore, the selectivity for catches of experiential trawls is poor. The negative influence on fishery resources and aquatic ecosystems cannot be ignored.Therefore, it is extremely urgent to formulate more scientific and reasonable management methods of recreational fishing gear. The result provides a theoretical basis for the management of recreational fishing boats.

Abstract:Based on the fisheries data from January to April 2013-2017, as well as the environmental data including the sea ice extent data in the Antarctica and sea water temperature data at depths of 54 m, 96 m, 193 m on the fishing ground, with the habitat suitability index (HSI) as an indicator of the habitat condition of Illex argentinus and variation of the areas with HSI>0.6 indicating the changes of suitable habitats, this study examined the relationship between sea ice extent and sea water temperature at different layers, and evaluated the influences of Antarctic sea ice variations-driven seawater cooling on HSI of I. argentinus in the Southwest Atlantic Ocean. Significant monthly variations were exhibited in the Antarctic sea ice extent, vertical water temperature and HSI of I. argentinus. A positive correlation was found between Antarctic sea ice extent and sea water temperature at different layers. The habitat quality of I. argentinus in the year with high sea ice extent was better than that in the year with low sea ice extent. Under the scenarios of vertical water temperature decreasing by 0.1, 0.3, 0.5 and 1.0 ℃ caused by the Antarctic sea ice melting, results suggested that with the decrease of vertical water temperature, spatio-temporal habitat pattern of I. argentinus showed significant changes. Suitable habitats of I. argentinus slightly enlarged with vertical water temperature decreasing no more than 0.5 ℃; while it clearly reduced under the scenarios of vertical water temperature decreased by 1.0 ℃. Large difference was found in the suitable habitats within different regions in the southwest Atlantic Ocean. Suitable habitat tended to move into the waters of the Exclusive Economic Zone (EEZ) off Argentina, and the percentage of suitable habitats within the EEZ off Argentina dramatically increased. Suitable habitats in the high seas had no evident changes. However, suitable habitats within the EEZ of Falkland Islands suffered great decrease. Our findings suggested that the great decreases of vertical water temperature induced by the sea ice melting in the Antarctica would lead to the inshore-ward movement of suitable habitats of I. argentinus off Argentina, while the suitable habitats would greatly decline within the EEZ of Falkland Islands.

Abstract:Based on the sea ice concentration data from the US National Snow and Ice Data Center, the distribution and trend of sea ice in the Bransfield Strait in recent 30 years are analyzed. The results show that the sea ice in Bransfield Strait is dominated by one-year ice, reaches the lowest in February and reaches the highest in August. There is obvious correlation between the years with low sea ice concentration and the strong El Niño years in the historical years.The trend of sea ice concentration in the Bransfield Strait in recent 30 years shows that the freezing month of sea ice was generally delayed and the sea ice concentration was mainly reduced.The analysis on ice concentration in three typical stations shows, the correlation between the sea ice in Bransfield Strait (Station A) and the sea ice in the north of the Strait mouth (Station B) is strong, while the correlation with the sea ice in the south of Bransfield Strait near the Weddell Sea (Station C) is weak.The recurrent neural network (RNN) model can be used to predict and analyze temporal variation in sea ice concentration, particularly in the years with low ice concentration level.

Abstract:Nowadays, countries around the world pay more and more attention to issues of fishery resources, ecological environment protection, food safety and labor force. The development of pelagic fisheries is in a new period of change. By studying the changes of fishing vessels, production and processing trade of pelagic fishing states in recent years, the development characteristics of the world's pelagic fisheries can be summarized as: the trend of vessel reduction is obvious among major pelagic countries, the fields and subjects of funding and investment become expanded and diversified, and the number of overseas bases is increasing besides bring more competitions. In condition of uneven distribution of global fishery resources, the process of liberalization and globalization of overseas trade continues to accelerate. Based on the development needs and directions of pelagic fishery industry of countries, to analyze the development trend of world pelagic fishery, it can concluded that countries are moving towards localization and standardized management in terms of the number of fishing vessels, scale of production, scope of investment, subject of investment and construction of overseas bases. The response to global fishery resources decline gets more powerful. Constructing traceability and standardization system and other primal issues are key tasks for sustainable development of pelagic fisheries.

Abstract:In order to improve the comprehensive utilization of aquatic products and develop new functional foods containing probiotic bacteria, by-product of fish processing-the grass fish scales was studied. The grass fish scales were hydrolyzed by flavourzyme,and the enzymatic hydrolysis process was optimized by the single factor experiments and the response surface methodology (RSM) using the proliferation of Streptococcus thermophilus as the evaluation index. The results showed that the optimum conditions were the reaction time 3.8 h, the ratio of material to water 1∶3.2 g/mL and the concentration of enzyme 6.2%. Under these conditions,the ΔOD₆₀₀ of proliferated Streptococcus thermophilus was 1.173 4±0.015 0. Meantime, the GFSH under the optimum conditions was further separated into 5 segments by membrane filtration, which were:<1 ku,1-<3 ku,3-<5 ku,5-<10 ku,≥10 ku. The effects of five segments on the growth curve and production of acid of Streptococcus thermophilus were studied. The results showed that in the 24-hour growth period of Streptococcus thermophilus, the fragments with molecular weights of less than 1 000 u significantly promoted the growth and acid production of Streptococcus thermophilus, and the ΔOD₆₀₀ of proliferated Streptococcus thermophilus was 1.050,and the pH of the medium was reduced by 1.06.

Abstract:Effect of flavor improvement on the largemouth bass fermented moderately by Lactobacillus plantarum, yeast and the compound bacteria was analyzed. Sensory analysis, electronic nose and monolithic material sorptive extraction combined with gas chromatography-mass spectrometry (MMSE-GC-MS) were used to detect the volatile flavor compounds of the bass after different microorganisms’ fermentation, while the changes of flavor compounds were analyzed before and after deodorization. The results of sensory evaluation and electronic nose analysis showed that there were distinctive differences in odor between different treated groups and the control. The results of GC-MS showed the contents of octanal, nonanal, decanal, 1-Penten-3-ol, 6-Methyl-5-heptane-2-one and other fishy odors were decreased to different degrees, due to being converted and utilized by microorganisms, indicating that the microbial fermentation had the effect on removing fishy odors. Among them, 2,3-pentanedione, geranylacetone and other volatile flavor compounds with pleasant odors such as creamy and floral aroma were produced in Lactobacillus plantarum treated group, which showed better coordinated flavors and effect of removing fishy odors combined with aroma enhancement.

Abstract:In order to study the quality changes of Mylopharyngodon piceus salted at different brine concentrations,taking Mylopharyngodon piceus as the experimental object, the quality changes of Mylopharyngodon piceus meat were analyzed and compared at different salt concentrations (7%, 10%, 13%) during salting for 48 h. The results showed that the range of pH changes was small in the whole salting process, but it generally showed a downward trend, and decreased with the increase of brine concentration. In the salting process, the water content of fish meat decreased with time, and decreased as the brine concentration increased, and the change of salt content in the fish meat was opposite. The free amino acids of fish meat were lost during salting. The thiobarbituric acid-reactive value (TBA) showed a trend of decreasing and then increasing in the salting process, and the increasing salt concentration would accelerate the oxidation degree of fish fat. The results of total viable counts (TVC) and total volatile basic nitrogen (TVB-N) showed that the samples of Mylopharyngodon piceus meat salted at the three brine concentrations all met the fresh standard within 48 h, and the higher the concentration, the better the effect. The results of sensory assessment showed that the sensory score of fish decreased with the increase of salting time, and the best quality was obtained when the fish was salted at 7% brine concentration for 4 h. The research results provided theoretical guidance for Mylopharyngodon piceus processing.

Abstract:To study the effect of chitooligosaccharides(COS) on aflatoxin B1(AFB₁)-induced toxic injury of rat liver cells (BRL 3A cells). The CCK-8 method was used to determine the IC₅₀ value of AFB₁ on cells and the non-damage concentration of COS on cells. After COS pretreated the cells for 6 hours and then adding AFB₁ to continue culturing for 24 hours, we used the kit to determine the cell viability, reactive oxygen species (ROS) levels, malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity and apoptosis rate. The mRNA relative expression levels of Nrf2, Keap1, Ho-1, Nqo1, Bax and Bcl-2 genes were determined by real-time quantitative PCR (RT qPCR), and the hierarchical clustering and enrichment pathways of differentially expressed genes were analyzed by RNA-seq. Results: The IC₅₀ of AFB₁ to BRL 3A cells was 15.86 μmol/L, and the COS concentration less than 125 μmol/L would not cause toxic damage to the BRL 3A cells. COS can reduce the increase of ROS level and MDA content in cells induced by AFB₁, enhance the activity of SOD and GST, thereby improve the cell's own antioxidant capacity and reduce the rate of apoptosis. AFB₁ can cause the significant expression of the pro-apoptotic gene Bax (P<0.05), and significantly reduce the transcription levels of Nrf2, Keap1, Ho-1, and Nqo1 (P<0.05), while COS pretreatment can significantly increase the expression of Nrf2, Keap1, Ho-1, Nqo1(P<0.05), and significantly reduce the expression level of Bax (P<0.05). In the results of RNA-seq enrichment pathways, COS may also alleviate the cytotoxic damage induced by AFB₁ through the metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450 and p53 signaling pathway (P<0.05). In summary,COS pretreatment can intervene the toxic injury of BRL 3A cells induced by AFB₁, which may be mediated by Nrf2 signaling pathway, metabolism of xenobiotics by cytochrome P450, drug metabolism-cytochrome P450 and p53 signaling pathway.