Abstract:Luster is the index to measure the maximum value of pearl. To study the relative contribution of Hyriopsis cumingii donor mussel and pearl mussel to the luster of nucleated pearls, white mussel (inner shell is white) is used as material, shell length and green shell are used as selection traits. According to different selection strategies, eight groups of H. cumingii populations were established. Each group was used as donor mussel and host mussel respectively for combined nuclear insertion. After 18 months of cultivation, it was found that: Among the different pearl breeding combinations, the pearl luster value of YAA pearl breeding combination from the selected population of group I was the greatest, which was 15.46% and 21.51% higher than that of YGG and YHH respectively. There was a significant difference in the luster of pearls cultivated by different groups of donor mussel. There was a very significant positive correlation between the inner shell luster of donor mussel and the luster of pearls (r=0.717-0.939). The regression equation between inner shell luster and pearl luster was established as follows: y=16.81+0.93x(R²=0.777).There was no significant correlation between the growth traits of donor mussel and the pearl luster. There were also significant differences in the luster of pearls cultivated by different groups of host mussels, but there was no significant correlation between the growth traits and luster of host mussels and the luster of pearls. The above results show that the breeding of H. cumingii with green shell color at the juvenile mussel stage has achieved the goal of improving pearl luster, which can be regarded as an indirect trait of breeding H. cumingii with high luster,the inner shell luster of donor mussel is significantly correlated with pearl luster, and the inner shell luster is better as the target trait.

Abstract:In order to investigate the genetic diversity and variation of different body colors of common carp (Cyprinus carpio), a total of 150 individuals from six different colored koi carp populations (Platinum Ogon, Higoi, Kohaku,Tajsho-sanke, Shiro Utsuri and Hi Utsuri), two colored FFRC No.2 strain common carp (grey and red) populations, and two hybrid carp populations (grey FFRC No.2 strain common carp♀ × Kohaku koi♂,Kohaku koi♀ × grey FFRC No.2 strain common carp♂) were analyzed based on mtDNA D-loop sequences. The results showed that the contents of A, T, G and C in the 932 bp D-loop sequence were 33.2%, 32.8%, 14.2% and 19.8%, respectively. In total, 34 variant sites were detected in all individuals, showing 18 haplotypes. Among them, there were two dominant haplotypes in Kohaku and Hi Utsuri, respectively. There were two unique haplotypes in white koi carp and grey FFRC No.2 strain common carp, and grey and red FFRC No.2 strain common carp shared one dominant haplotype. The genetic distances across the ten populations ranged from 0.001 to 0.018, with F_ST values ranging from 0.011 to 0.933. The analysis of molecular variance (AMOVA) revealed that there was 67.17% variation among varieties and 32.83% variation within varieties, indicating highly substantial genetic difference. It demonstrated that the Hi Utsuri, white koi carp, and Tajsho-sanke had high genetic diversity, while the Shiro Utsuri, FFRC No.2 strain common carp (grey and red), and hybrid carp had high genetic purity. The study enriched the genetic data of the various body color carp germplasm resources and provided the guidance for germplasm resource utilization and genetic selection in the future.

Abstract:In the present research, the effects of density (60 and 120 individuals /m²) and salinity (20 and 30) are examined on osmotic regulation and antioxidant responses of Sinonovacula constricta. The experiment lasted 72 hours. The concentration of Na⁺ and K⁺ in the hemolymph, the activity of SOD and MDA in liver, the activity of Na⁺/K⁺ -ATPase, and the expression of Na⁺/H⁺ antiporter and V-ATPase genes in gill were measured. The results showed that density and salinity had no significant interaction on Na⁺ and K⁺ concentration of the hemolymph. Na⁺ and K⁺ concentrations in high-salinity group were significantly higher than those in control group. The effects of density and salinity on Na⁺/K⁺ -ATPase activity had significant interaction at 12 h and 24 h. Na⁺/K⁺-ATPase activity in high-salinity group and high-density group was significantly higher than that in control group. SOD activity and MDA content in all experimental groups were significantly higher than those in control group, and density and salinity had significant interaction on SOD activity and MDA content. The expression of Na⁺/H⁺ antiporter and V-ATPase genes in high-salinity group and high-density groups were significantly higher than those in control group. Therefore, high density and salinity performed significant interactive effect on osmotic regulation and antioxidant level of S. constricta. The results provided a theoretical reference for further exploring the response mechanism of marine shellfish to density and salinity.

Abstract:In order to explore the regulation mechanism of alkali resistance of Leuciscus waleckii, a dominant natural species in an alkaline water environment, gill cells of Leuciscus waleckii were cultured by trypsin digestion in vitro, and the suitable conditions for primary and subculture cell culture were determined. The tolerance experiment was carried out to demonstrate its growth characteristics in an alkaline environment. The experimental results show that the primary gill cells of Leuciscus waleckii can be cultured in a DMEM medium containing 10% Fetal bovine serum(FBS) at 15 ℃, which can obtain a stable and good culture effect. It can be passaged within 36-72 h, and the stably passaged cells are named LWG cells. During subculture, LWG cells grew and metabolized vigorously at 36 h, which can be used for subsequent experiments. In alkaline water habitat, gill cells will start the osmotic pressure stress response mechanism to alleviate the damage caused by alkali ions to fish. Therefore, an alkali stress experiment on LWG cells was carried out and their cell activity and function were tasted. It was found that when LWG cells tolerated for three hours the concentration of 25-50 mmol/L NaHCO₃, proliferation rate was about 60% and apoptosis occurred. It can be inferred that LWG cells have strong osmotic alkalinity tolerance and promote apoptosis under carbonate alkalinity stress of 25-50 mmol/L. This will provide stable experimental materials for exploring osmotic stress response mechanisms and verifying related gene functions under alkali stress.

Abstract:The complete sequence of the mitochondrial genomes of 21 species in the Penaeidae were comprehensively analyzed, and the results showed that the length of the mitochondrial genome is 15 893 to 16 071 bp, A+T content is from 64.59% to 70.61%. The K_a/K_s analysis showed that among 13 protein-coding genes (PCGs) in the mitochondria of Penaeidae species, the K_a/K_s of atp8 gene was the highest, indicating that the atp8 gene may have subjected to relatively weak selection pressure in Penaeidae. In the analysis of the different sites, it was found that the nd5 and rrnL genes were ideal molecular markers. And the codon usage analysis showed that the encoded amino acid preferences were similar. At the same time, more systematic and comprehensive ML (Maximum likelihood) and BI (Bayesian inference) methods were adopted to construct a phylogenetic tree. The results showed that the topological structure of the phylogenetic tree constructed by these two methods was completely the same, and the species of the same genus were also classified into one category or separated into a branch. This study provides reliable molecular markers for the rapid identification of Penaeidae species, and provides a theoretical basis for analyzing the genetic diversity of Penaeidae species.

Abstract:In order to find out the correlation among the quantitative characters and influencing factors of production of Macridiscus multifarius, high phenotypic traits shell length (SL), shell height (SH), shell width (SW), body mass (BM) of randomly selected different geographic groups of wild equilateral shallow clam in Zhoushan, Zhejiang Province were measured, and relationship between morphological traits and weight traits of M. multifarius was analyzed by path analysis. The results showed that the effects of morphological traits on body mass were different between the two populations, and shell height had the greatest influence on body mass in Shengsi population, while shell width was the most influential trait on body mass in Putuo population. The correlation coefficients between morphological traits and body mass of the two populations were great and with extremely significant correlation. The indirect action of morphological traits on body mass was greater than the direct action. The regression equations of variables with significant partial regression coefficients for body mass were expressed as Y=0.505X₁ + 0.773X₂ + 0.723X₃-41.313, Y =0.258X₁ + 0.432X₂ + 0.888X₃ -23.607, where Y represents body mass, X₁, X₂ and X₃ represent shell length, shell height and shell width, respectively. The regression coefficients of the two equations are extremely significant. The results showed that the shell height of Shengsi population was an ideal index to measure the body weight in the breeding of the equilateral shallow clam, while the shell width of Putuo population should be paid attention to, and this may provide a theoretical basis for the breeding of M. multifarious.

Abstract:In order to study the differences of muscle nutritional components of Litopenaeus vannamei in multistory culture mode Takifugu obscurus + L. vannamei + Ipomoea aquatica) and monoculture mode, biochemical analysis method was used to analyze and compare the nutritional components of L. vannamei in these two culture modes. The results showed that the moisture, crude protein, and crude ash contents of shrimp muscle from multistory culture mode were 77.17%, 21.38% and 1.39%, respectively, which did not differ from monoculture model (74.96%, 22.40% and 1.40%, respectively), but the content of crude fat of the monoculture mode (1.02%) was significantly higher than that of the multistory culture mode (0.80%). 18 kinds of amino acids have been detected in L. vannamei muscle from two culture modes. Among the detected amino acids, 3 kinds of amino acids (tryptophan, glycine, and arginine) of the multistory culture mode were observed to be significantly higher than those of the monoculture mode. In addition, the significantly higher values of threonine, serine and methionine were found in multistory culture mode when compared to the monoculture mode. However, contents of alanine and proline in L. vannamei from multistory culture mode were significantly lower than those of the monoculture mode. The other 10 kinds of amino acids between the monoculture model and the multistory culture model did not differ significantly. The contents of total amino acids (TAA), essential amino acids (EAA) and non-essential amino acids (NEAA) in L. vannamei muscle of the multistory culture model (86.08%, 31.19% and 44.17%) were slightly higher than those of the monoculture model (82.76%, 30.11% and 43.00%), but not differing significantly between two culture modes. The content of delicious amino acids (DAA) in L. vannamei muscle of the multistory culture mode (33.51%) was significantly higher than that of the monoculture mode (31.44%). Similarly, the content of half-essential amino acid (HEAA) (10.71%) of the multistory culture model was significantly higher than that of the monoculture mode (9.65%). No significant differences were observed in the essential amino acid index (EAAI) and the ratio of branched chain amino acids to aromatic amino acids (F-value) between the monoculture mode (72.46, 2.14) and the multistory culture mode (72.65, 2.13). The proportion of saturated fatty acids (ΣSFA), monounsaturated fatty acids (ΣMUFA) in L. vannamei muscle of the multistory culture mode (32.70%, 24.70%) were found to be higher than those of the monoculture mode (32.40%, 24.33%), but no significant differences were noted. In contrast, the multistory culture model reported lower values in the proportion of polyunsaturated fatty acids (ΣPUFA) and EPA+DHA (42.61%, 8.84%) when compared to the monoculture mode (43.27%, 10.82%), but no statistically significant differences were observed. The results indicated that no significant differences in main common nutrient components in L. vannamei muscle were found between the two modes, but positive effects have been observed in growth performance in multistory culture mode as shrimp individuals can reach a bigger commercial size and the meat is more delicious according to amino acid analysis. Moreover, the multistory culture mode has the advantages of both ecological and economic benefits as it meets the reguirements of low-carbon and green development, so it is worth promoting.

Abstract:The growth and cell composition of a newly isolated strain of Chlorella pyrenoidosa SHOU-1002 were compared in three mixotrophic groups (treated with glucose, sodium glutamate and yeast extract, respectively), and a photoautotrophic group. The results showed that, generally, the cell density of mixotrophic groups were significantly higher than that of the photoautotrophic group after inoculation. Moreover, the cell density of the glucose group was significantly higher than that of the sodium glutamate group and the yeast extract group within 6 days after inoculation. Additionally, there was no significant difference in the cell density of the three mixotrophic groups from the 10th day. On the 12th day, the contents of chlorophyll a, carotenoids, protein and total lipid in the sodium glutamate group and yeast extract group were significantly higher as compared to those in the glucose group; however, the carbohydrate content was significantly lower compared to the glucose group. Further, in the glucose group, SFAs increased while the PUFAs decreased with the prolongation of culture time. The PUFAs in the sodium glutamate group and the yeast extract group tended to decrease in the beginning, then they increased. The PUFAs of the sodium glutamate group and the yeast extract group were significantly higher than that of the glucose group on the 12th day. In conclusion, the results suggested that Chlorella pyrenoidosa SHOU-1002 had the ability of mixotrophy and its growth efficiency was significantly improved in mixotrophic mode. Besides, the algal cells cultured by yeast extract or sodium glutamate had higher nutritional value than those cultured by glucose.

Abstract:Hepu mitten crab (Eriocheir hepuensis)is mainly distributed along the coast of Guangxi. It has important economic value and breeding potential. There is no report on the edible yield and nutritional composition of HP. Therefore, this study used wild Chinese mitten crab (Eriocheir sinensis) in the Yangtze River as a control to determine and compare the edible yield, color parameters, total carotenoid content, proximate composition and fatty acid composition of wild HP and CJ adult crabs. The results showed: The edible yield of HP male was significantly lower than that of CJ male, but there was no significant difference in the gonadal index, hepatosomatic index and the meat yield between Hepu mitten crab and Chinese mitten crab; Regardless of male and female, the a^* and b^* values of the wet carapace of HP crab were significantly higher than those of CJ, and the total carotenoid content of HP male hepatopancreas was significantly higher than that of CJ male; The moisture of HP female in gonad was significantly higher than that of CJ female, but the lipid of muscle of HP female was significantly lower than that of CJ female,and the moisture and the protein content of HP male in muscle were significantly lower than those of CJ male;ΣSFA in HP female hepatopancreas, C18∶ln,ΣMUFA, DHA/ EPA in muscle and C18∶0, C20∶1n9 in ovaries were all significantly higher than CJ female,and HP male hepatopancreas contained higher C22∶6n3 and ΣPUFA while hepatopancreas had higher C22∶6n3, ΣPUFA than CJ male. In summary, similar tissue indices are found between HP and CJ, but there are differences in proximate composition, carotenoid content, and fatty acid composition. This may be related to their genetics and growth environment.

Abstract:To investigate the effects of different levels of cottonseed meal added to the feed on the growth, skin color, flesh color, serum biochemical indices and intestinal flora structure of channel catfish (Ictalurus punctatus), seven hundred and fifty channel catfish with an initial body mass of (49.95 ± 0.05) g were selected and randomly divided into three groups of five nets each, with 50 fish in each net cage. The base feed without cottonseed meal substitution was used as the control group, and three isonitrogenous and isolipid test feeds were formulated with 7% (group M1) and 14% (group M2) cottonseed meal replacing 25.8% and 51.7% of soybean meal in the base feed, respectively for 60 days. The experimental results showed that: Compared with the control group, cottonseed meal substituted for soybean meal had no significant effect on weight gain rate, feed coefficient and morphological indexes of channel catfish; Cottonseed meal substituted for soybean meal had no significant effect on serum levels of complement 3, complement 4, total cholesterol and triglycerides; Compared with the control group, cottonseed meal substituted for soybean meal had no significant effect on lateral skin of channel catfish, but the high cottonseed meal group (M2) significantly increased the brightness of the abdominal skin; cottonseed meal significantly increased the redness of the back muscles of the channel catfish, but there was no significant change in the brightness and yellowness values among the treatment groups. The cottonseed meal group had no significant effect on the brightness, redness and yellowness of the abdominal skin of the channel catfish. Compared with the control group, the low cottonseed meal feed (M1) significantly reduced the relative abundance of Fusobacteria and significantly increased the relative abundance of Firmicutes. In conclusion, when cottonseed meal in the feed was replaced by less than 51.7% soybean meal, it did not affect the growth performance of channel catfish, but it affected the skin color and flesh color of the fish.

Abstract:In order to explore the changes of nutrients in the fertilized eggs of Australian freshwater lobster during development, the fertilized eggs in the egg-nauplius stage, the embryo with eye pigment forming stage, the prepare-hatchling stage and newly hatched shrimp were systematically analyzed in this study. The results showed that, moisture content in fertilized eggs increased significantly with the development of fertilized eggs to newly hatched shrimp, crude protein and lipid content decreased significantly with the development process, the ash content of newly hatched shrimp was the highest; Total amino acids, essential amino acids, and flavoring amino acids content of fertilized eggs decreased significantly with the development process; Based on the nutritional evaluation by amino acids score (AAS) and chemical score (CS), (Met+Cys) was the first limiting amino acids of fertilized eggs and newly hatched shrimp; EAAI of fertilized eggs and newly hatched shrimp decreased significantly with the development of fertilized eggs to newly hatched shrimp; 10 main fatty acids were detected in fertilized eggs and newly hatched shrimp of Australian freshwater lobster, and the contents of PUFA and DHA in newly hatched shrimp were significantly lower than those in fertilized eggs, but the content of EPA+DHA was significantly higher than that of fertilized eggs. In conclusion, the content of ash and EPA+DHA of newly hatched shrimp were significantly higher than those of fertilized eggs, so the addition of calcium dihydrogen phosphate and EPA+DHA can be appropriately increased in the preparation of open bait for Australian freshwater lobster larvae.

Abstract:In order to analyze the impact of data uncertainty on the results of fish-index of biological integrity(F-IBI), a F-IBI was constructed based on the historical information and ecosystem characteristics of the surrounding waters of Chongming Island, China. A total of 12 indices related to fish species composition, trophic structure, tolerance, reproductive character, heath conditions and biomass were included in this F-IBI. Fish community information in waters near Chongming Island were collected from surveys in August and November 2020. The F-IBI was used to evaluate the state of ecosystem health of study area. Besides, the effects of survey data uncertainty on the projection of F-IBI for the surrounding waters of Chongming Island were evaluated by computer simulation. Five indices (total number of fish species, percentage of number of pollution sensitive fishes, percentage of number of piscivorous species, percentage of number of adhesive egg fishes and catch per haul per hour) from 12 indices were selected as simulation indices. The effect of single index uncertainty, multiple indices uncertainty and different levels of uncertainty on the final estimation result of F-IBI were evaluated. Results indicated that the F-IBI was in the "poor" grade of the surrounding waters of Chongming Island in August and November 2020. Uncertainty analysis showed that a set of 30% at the coefficient of variance of indices did not affect the evaluation grade of F-IBI, but the score changed to a certain extent.With the increase of index uncertainty, the fluctuation range of the evaluation results of F-IBI increased gradually. The influence strength of each index was related with the position of survey data in the range in the scoring section of F-IBI system. The results of this study emphasize the importance of considering the natural fluctuation range of the evaluation index in the evaluation of F-IBI in waters near Chongming Island.

Abstract:As a representative of the Channichthyidae in Southern Ocean, Mackerel icefish (Champsocephalus gunnari) not only has important economic values in fishery, but also plays a vital role in the Antarctic marine ecosystem. C. gunnari feeds mainly on Antarctic krill (Euphausia superba) and is also the prey of higher predators. It is very important to study the feeding habits of C. gunnari for understanding the variations in E. superba resources and predicting the survival and development of high-trophic organisms. The results of this study showed that the diet of C. gunnari can be divided into two groups, of which E. superba was dominant in the diet composition, and the frequency and quantity percentage were 100% and 99.9% respectively. The remaining diet was Themisto gaudichaudii. The results of Generalized Linear Model showed that the number of E. superba in the stomach of C. gunnari increased with the distance of sampling locations to the South Orkney Islands. The relationship between standard length and stomach content mass of C. gunnari was S_M=6.639 6e^{0.017 9L}. Stomach content mass and daily consumption increased with the increased standard length, while daily consumption percentage remained between 0.98% and 2.08%. The results of this study can provide basic information for understanding the feeding ecology of C. gunnari and provide data for resource conservation of C. gunnari in the South Orkney Islands.

Abstract:To further clarify the effect of lethal conditions on the quality of grouper(Epinephelus lanceolatus) and to improve the quality of grouper during refrigeration, five different lethal methods were used to treat grouper, with the following groups: Ⅰ: lethal by ice burial; Ⅱ: lethal by knocking on the head; Ⅲ: lethal by subjecting live grouper to temperature gradients of 18, 14, 10 and 6 ℃ (each temperature treatment for 20 min); Ⅳ: lethal by subjecting live grouper to temperature gradients of 18, 12 and 6 ℃ (20 min at each temperature); Ⅴ: lethal by subjecting live grouper to temperature gradients of 18, 6 ℃ (20 min at each temperature). The grouper was then rapidly reduced to 0 ℃ in the centre of the fish body by micro-freezing machine and refrigerated at 0-4 ℃. The effects of changes in the sensory evaluation, textural characteristics, pH, lactic acid content, sulfhydryl content, volatile salt nitrogen (TVB-N), total bacterial colony count and other quality evaluation indicators of the fish during the freezing period were subsequently measured and analyzed. The results showed that the five groups of lethal treatments had significant effects on the quality of fish meat during refrigeration, in descending order: sensory evaluation and TVB-N: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, texture: group Ⅳ> group Ⅴ> group Ⅱ> group Ⅰ> group Ⅲ, lactic acid content and pH: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, sulfhydryl content and total bacterial colony: group Ⅰ> group Ⅱ> group Ⅴ> group Ⅳ> group Ⅲ. ＞ group Ⅳ＞ group Ⅲ. This indicated that the lethal treatment by gradient cooling was significantly better than the lethal treatment by head knocking and ice burying, and the temperature difference interval in gradient cooling should not be too wide. The results of the quality evaluation of all the indicators showed that group Ⅲ had the best lethal treatment, as the narrower temperature range made the process of grouper death less stressful, and the lactic acid content, pH and total sulfhydryl group were relatively stable, which was more effective than the other four groups in delaying the reduction of textural characteristics and sulfhydryl group content and inhibiting microbial activity, thus prolonging the shelf life of the fish samples.

Abstract:The Chinese mitten crab (Eriochier sinensis) is a unique freshwater aquaculture crab in China, with delicious taste and high nutritional value. At present, the relevant research on the element composition in its body mostly focuses on the unprocessed Chinese mitten crab, and it is not clear whether the cooking method will affect the element distribution in its body. Therefore, the effects of different cooking methods on the distribution of Na, K, Mg, Mn, Fe, Cu, Cr, Cd and Hg in the edible parts of Chinese mitten crab were studied by ICP-MS. The results showed that before cooking, the distribution of elements in the edible parts of Chinese mitten crab was as follows: K>Na>Mg>Fe>Cu>Mn>Hg>Cr>Cd. Compared with the element content in the unprocessed edible parts, after cooking, the content of K decreases, and the content of Na and Mg elements increases as a whole. The content of other elements varies with different cooking methods, parts and genders. There is a significant difference between the same element (All samples are dry weight). Health risk assessments based on three heavy metals showed that THQ values were less than 1 before and after cooking and did not pose a significant risk to human health. Studies have shown that cooking methods have an impact on the changes of element content in different parts of Chinese mitten crab, but will not increase the risk of heavy metals to human health. This study aims to make up for the shortage of risk assessment of heavy metals in Chinese mitten crab with food raw materials as the research object, and provide theoretical and data support for the precise dietary risk of Chinese mitten crab.

Abstract:Shiga toxin-producing Escherichia coli (STEC) is a zoonosis and food-borne pathogenic bacterium. It is necessary to understand its characteristics and potential pathogenicity and analyze the production ability of Shiga toxin (Stx) in the biofilm state. The traditional PCR was performed to amplify the stx variant gene subtype. The results showed that strain 1 carried stx1c+stx2d subtype, strain 2 carried stx1+stx2f subtype, and strain 3 carried stx2e subtype. The results of multilocus sequence typing (MLST) showed that the three strains were relatively distantly related and possessed genetic diversity. The crystal violet staining test and the cytotoxicity test of Vero cell were used to explore the biofilm-forming ability and Stx-producing ability at 4 ℃, 10 ℃, 25 ℃, and 37 ℃. It showed that temperature significantly affected the biofilm-forming ability and Stx-producing ability. All STEC strains had the strong ability of biofilm formation and Stx production at 37 ℃. The results of the cytotoxicity test of Vero cell showed that strain 2 had the weakest Stx-producing ability under the four different temperature conditions and strain 3 showed strong biofilm-forming ability and Stx-producing ability. Especially at 4 ℃and 10 ℃, strain 3 had the strongest biofilm-forming ability compared to strain 1 and stain 2. Retail meat in China is contaminated with STEC which could be potentially pathogenic. Especially with the discovery of strains with strong biofilm-forming ability and Stx-producing ability, we should strengthen the monitoring of STEC during food processing.

Abstract:Favourable water quality is the basis of pond healthy aquaculture. In order to realize the automation of monitoring and sampling, an integrated unmanned water quality monitoring and sampling boat was designed and its performance test was carried out. Considering the requirements of water quality monitoring and sampling, the hull structure was designed, and the layout of the functional areas of water quality sensor, sampling system, power supply, control box, and water sample collection bottles in the cabin was designed considering the load bearing and stability. The autonomous cruise control system was developed based on the differential twin-propellers driven model and the integration of GPS and attitude sensor. The water sampling control system and water quality monitoring data platform were integrated with Internet of Things technology. The comprehensive test results showed that the trajectory of unmanned boat was accurate, the maximum deviation of monitoring point was 1.49 m, the minimum deviation was 0.39 m, and the average deviation was 1.003 m. The water quality monitoring and sampling function was stable, and the pH value, water temperature and dissolved oxygen of water could be returned in real time. Six 500 mL water sampling bottles could collect water samples of underwater 50 cm accurately, which is in line with national standards. The results provide a low-cost and reliable implementation scheme for the whole surface water quality monitoring of aquaculture.

Abstract:Aiming at the domestication demand in the process of proliferation and release of marine ranching,in order to improve the effectiveness,reliability and operation convenience,a fish acoustic domestication device based on EVA material was designed,and the application experiment of the device was carried out. Taking EVA solid material as the floating body,the overall structure of fish domestication device which integrates remote control,acoustic domestication and fish behavior monitoring was designed. The natural feeding angle at the bottom of the hopper was determined according to the characteristics of domesticated bait,and the screw feeding control device is adopted to realize the uniform feeding of bait as required, with the feeding amount of 113 g per minute. The overall average daily power consumption of each subsystem is 27.47 Wh,and a solar energy supply system is designed to meet the needs of regular work of 13 consecutive rainy days. According to the calculation, the metacentric height of the device is 0.37 m, which meets the requirements of the code, and the natural period of rolling is 2.3 s, which avoids the main wave energy frequency, indicating that the device has good wave-following motion characteristics. The acoustic domestication experiment of Oplegnathus fasciatus was carried out. The experiment showed that after 25 times of domestication,taking the aggregation rate of 40% fish in the range of 1 meter in diameter at the domestication point as the standard,the aggregation duration of the control pool was 28 seconds,the aggregation duration of the simple domestication experimental pool was 115 seconds,and the aggregation duration of the integrated domestication experimental pool was 473 seconds. From the perspective of the change of fish aggregation rate,the simple domestication experimental pool tended to be stable at about 49% and finally reached 58% after 12 times of domestication while the integrated domestication experimental pool tended to be stable at about 95% and finally reached 99% after 8 times of domestication. The developed device has been applied in net cages and open sea areas,and good results show its effectiveness and reliability,which provides solid foundation to improve the fries releasing effect.

Abstract:The biochar substrate is a new type of filler. In this study, we detected the physical properties of biochar substrate, and investigated the effect of adsorption biofilm in treating artificial wastewater and pond effluent compared to gravel quartz sand group. The results showed that: (1) the main components are SiO₂, CaCO₃ and other carbonates and oxides, which are non-toxic and harmless, and the specific surface area of the biochar substrate is large (8.92 m²/g). (2) when the water temperature is around 21 ℃, the more substrates added, the more significant the effect of reducing nitrogen and phosphorus. When the added amount was 45 g/L, the removal rate of ammonia nitrogen at 159 h was 91.58%; when the added amount was 20 g/L, the removal rate of orthophosphate at 120 h was 94.12%. (3) at water temperature around 15 ℃, when the addition amount is 20 g/L, the ammonia nitrogen reduction effect of the group of biochar substrate is better than that of gravel and quartz sand, but the effect of gravel and quartz sand in reducing chemical oxygen demand from pond sewage is better. In summary, in addition to its own ability to reduce nitrogen and phosphorus, the biochar substrate has a stronger ability to attach biofilms, has better water purification capabilities, and has a good potential application.

Abstract:In vitro experiments were conducted to study the effects of Onchidium reevesii polysaccharides and sulfated Onchidium reevesii polysaccharides on the growth of Hela human cervical cancer cells, and with positive drug cisplatin (0.5, 0.75, 1.5 μg/mL) as control. Different mass concentrations (50, 75, 150 μg/mL) of OSP and S-OSP were applied to Hela cells, and we used CCK-8 method to analyze the proliferation of Hela cells at 12, 24, 48 and 72 h, and analyzed the cell cycle with flow cytometry, and used qRT-PCR to detect the expression changes of related apoptosis genes. The results show that both OSP and S-OSP can reduce the viability of Hela cells and induce their apoptosis, moreover, S-OSP can more significantly inhibit the proliferation activity of Hela cells than OSP, It shows that the sulfation modification changes the structure of the polysaccharide and affects the anti-tumor activity of the polysaccharide. After 48 hours of treatment, the growth inhibition rates of Hela cells in the three concentrations of OSP group were 60%, 67%, and 71%, respectively; the growth inhibition rates of Hela cells in the S-OSP group were 74%, 77%, and 84%, respectively; the growth inhibition rates of Hela cells in the cisplatin group were 82%, 86%, and 90%, respectively. Flow cytometry showed that after OSP and S-OSP had acted for 24 h, the ratio of early and late apoptosis of cells was significant, and increased proportion of cells in G0/G1 phase, and the proportion of S-phase cells continued to decrease; Real-time fluorescence quantification showed that the expression of pro-apoptotic gene Caspase-3 increased significantly with the increase of drug mass concentration, and the expression of anti-apoptotic genes Bcl-2 and Bcl-xL did not change significantly with the increase of drug mass concentration. It shows that OSP and S-OSP can induce Hela cell apoptosis by regulating the Caspase signaling pathway.