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Optimization of ratio of refrigerants for quick liquid freezing of aquatic product by response surface methodology
Tao ZHANG, Yanyan WU, Laihao LI, Xianqing YANG, Wanling LIN, Shaoling YANG, Shuxian HAO
Third Proofread  doi: 10.12131/20190038
[Abstract](760) [FullText HTML](150) [PDF 4079KB](9)
In order to develop a safe food-grade quick-freezing liquid formulation suitable for rapid freezing of aquatic products, we designed a low-temperature quick freezing liquid which composed of ethanol, oligofructose, citric acid, calcium chloride and propylene glycol. Then, we analyzed the variation of freezing point with different mass fractions of that composition by single factor test. Based on that, taking the freezing point and viscosity as response values, we optimized the addition amount of the refrigerants in the quick freezing liquid by Box-Behnken response surface method. The optimum formula of quick-freezing liquid was 19.9% ethanol, 9.5% fructooligosaccharide, 3% citric acid, 5% calcium chloride and 10% propylene glycol. The quick-freezing liquid prepared by the formula had a freezing point of –63.50 ℃ and a viscosity of 4.64 mPa·s, characterized by low freezing temperature, small viscosity, low formulation cost and convenient operation, suitable for rapid freezing of aquatic products and frozen convenience foods.
Biological study of reproductive characteristics of Acanthopagrus schlegeli in Daya Bay
Defang CHEN, Teng WANG, Yong LIU, Yayuan XIAO, Jiujiang WANG, Chunhou LI
Third Proofread  doi: 10.12131/20190051
[Abstract](747) [FullText HTML](171) [PDF 1126KB](9)
We collected 721 individuals of Acanthopagrus schlegeli in Daya Bay in January, March, April, August−December, 2018, and then investigated the annual variation of reproductive characteristics of A. schlegeli in Daya Bay so as to provide a theoretical basis for its artificial breeding and conservation. The results show that: 1) the spawning period falls between November and March. The total length ranged 175−487 mm for females [averge (297.92±56.61) mm]. The body mass ranged 90.96−1 907.12 g for females [average (511.36±307.53) g]. The total length ranged 110−440 mm for males [average (237.61±61.05) mm]. The body mass ranged 21.92−1 370.00 g for males [average (277.76±210.33) g]. The full lengths of females were significantly longer than those of males (P<0.001). 2) The gonad maturity coefficient and gonad development indicate that the reproductive period of A. schlegeli in Daya Bay was from November to March. 3) The existence of androgynous individuals indicates that the species will undergo sexual reversal, and the males will mature first and then change to females. 4) The total lengths (TL) at 50% sex maturity for females and males were 248.52 mm and 148.03 mm, respectively. 5) A. schlegeli is a multiple spawner with indeterminate fecundity by oocyte size-frequency distributions. The number of the individual fertility ranged from 84 100 to 2 655 168 granules (average 728 732±499 547). The relative fertility of total length was 380.54−8 271.55 eggs·mm−1 [(2 731.44±1 630.93) egg·mm−1]. The relative fertility of body mass was 277.58−3 592.83 eggs·g−1 [average (1 443.87±766.82) eggs·g−1]. There was a linear correlation among absolute fecundity and total length, body mass and gonadal mass.
Assessment of allowable catches and exploitation state of marine fishery resources in Pakistani coastal waters
Kui ZHANG, Ping GENG, Dengfu SHI, Youwei XU, Panhwar SHER KHAN, Zuozhi CHEN
Third Proofread  doi: 10.12131/20190065
[Abstract](811) [FullText HTML](174) [PDF 1645KB](17)
According to the catch statistics data during 1950−2015, we applied a Catch-MSY model to estimate the allowable catches and maximum sustainable yields (MSYs) for 24 commercial fish groups and total allowable catch (TAC) in Pakistani coastal waters. Results show that MSY and TAC in Pakistani coastal waters were 40.53×104 t and 36.47×104 t, respectively. The total catches in 2015 were less than MSY, suggesting that the fisheries are not overfished. The MSY results show that eight fish groups (cobia, barracudas, groupers, butterfishes, common dolphinfish, dorab wolf-herring, crevalle jack and largehead hairtail) have been overfished at present since the catches in 2015 exceeded MSY. At present, the marine fishery resources in Pakistani coastal waters are fully exploited. Most commercial fish groups are overfished or recovering after collapse and their development potential is relatively small. It is recommended to exploit oceanic fishery resources such as Sthenoteuthis oualaniensis in Arabian Sea in future fisheries development.
Advance in marine algicidal bacteria research
Honghui HUANG, Beibei HAN, Shufei ZHANG, Fengxia WU
Third Proofread  doi: 10.12131/20190040
[Abstract](302) [FullText HTML](150) [PDF 650KB](11)
As a notorious environmental issue, harmful algal blooms (HABs) severely threat the marine ecosystem, aquaculture and human health around the world. Therefore, it has been a research hotspot to develop a more environment-friendly and effective agents to control the HABs. In recent years, a lot of marine bacteria have been found to inhibit algal growth or lyse the algae through direct or indirect attacking. Utilizing marine algicidal bacteria to control HABs can maintain balance of water ecosystem. The algicidal bacteria show broad application prospects in HABs control because of its secure and high efficiency. In this paper, the development of algicidal bacteria, algicidal mechanism and their applications are summarized, and the future prospects in theoretical research and application fields are discussed.
Bacteriostasis and safety evaluation of two lactic acid bacteria
Kai CHEN, Ludan ZHU, Hongliang TAN, Dongyu HUANG, Bingwen XI, Liangkun PAN, Jun XIE
Third Proofread  doi: 10.12131/20190012
[Abstract](573) [FullText HTML](169) [PDF 1058KB](11)
In this study, two strains of lactic acid bacteria [Lactobacillus casei (S60) and L. plantarum (S72)] were tested by aseptic technique, including routine biochemical detection, susceptibility test, in vitro bacteriostasis test and animal experiment. Their feasibility and safety as probiotics for fishing were also verified. Results show that the two lactic acid bacteria could tolerate acid (pH 4.0) and bile salt (0.1%), and exhibit different antibacterial activities against six pathogens including Aeromonas hydrophila. The results of antimicrobial substances analysis shows that the effective antimicrobial substances were related to the organic acids produced in metabolic process. The results of safety evaluation shows that the two strains of lactic acid bacteria had no ability to decompose gelatin and hemolysis. The results of death statistics and blood biochemical indicators show that the intraperitoneal injection of live bacteria as high as 1.0×109 CFU·mL−1 did not cause serious death and body injury in experimental fish. It is included that the two strains of lactic acid bacteria have high safety as oral probiotics. Drug resistance studies show that the two strains of lactic acid bacteria had strong tolerance to aminoglycosides and sulfamethoxazole, and were sensitive to ampicillin, enrofloxacin, florfenicol and doxycycline. Therefore, the application of the two strains of lactic acid bacteria should pay attention to the selection of drugs in management process.
Changes of pigment-related enzyme activity and gene expression at early developmental stage of koi carp
Haoran YIN, Mingkun LUO, Lanmei WANG, Zaijie DONG, Wenbin ZHU, Jianjun FU
Third Proofread  doi: 10.12131/20190023
[Abstract](518) [FullText HTML](173) [PDF 3357KB](10)
We investigated the changes of tyrosinase and cystinase activities, as well as the expressions of tyr, mitf, agouti and mc1r mRNAs at the early developmental stage of Kohaku and Hi-Utsuri koi carp (Cyprinus carpio) by using histological observation, enzyme-linked immunoassay and quantitative reverse transcription-polymerase chain reaction methods. The results show that the hatched carps became light yellow and translucent. The melanocytes occurred on 8 dph (day-post-hatching). The activity of cystinase increased with the koi carp development, and no significant difference was observed between Kohaku and Hi-Utsuri groups before 7 dph (P>0.05), while Hi-Utsuri group showed significantly higher enzyme activity than Kohaku group at the same stages after 7 dph (P<0.05). Tyrosinase activity showed an up-regulation trend with slight fluctuation during the development of koi carp, and peaked at the ocular pigment stage and on 23 dph (P<0.05). The enzyme activity was significantly higher in Hi-Utsuri group than in Kohaku group at each developmental stage (P<0.05), which indicates that tyrosinase and cystinase activities were closely associated with pigment cell development of koi carp. The expressions of agouti, mc1r, mitf and tyr mRNAs peaked in gastrula and blastula periods (P<0.01), then decreased. Thus, agouti, mc1r, mitf and tyr mRNAs might play an important role in the formation of body colors in early embryonic development.
Investigation of Grateloupia on floating raft in Nan'ao, Shantou of Guangdong Province and Dongshan of Fujian Province
Bin FENG, Ting LI, Bo Zhang, Changbo ZHU, Jiaqi SU, Suwen CHEN, Xianqing YANG
Third Proofread  doi: 10.12131/20190050
[Abstract](1193) [FullText HTML](388) [PDF 12442KB](11)
In order to promote the development and utilization of Grateloupia and provide reference for its food and processing, we investigated the species composition, biomass, growth environment and mouthfeel of Grateloupia on floating rafts in Nan'ao, Shantou, Guangdong Province and Dongshan, Fujian Province once a month from January to April 2018. The results show that the water velocity and temperature were 0.039−0.985 m·s–1 and 19−23 ℃, respectively, and the water velocity in Dongshan was greater than that in Nan'ao. By morphology, cross-section and rbcL sequence analyses of the samples collected from the floating raft, we found eight Grateloupia species (G.lanceolata, G. turuturu, G.taiwanensis, G.carnosa, G.livida, G. haimensis, G. prolongata and G. sparsa). The dominant species were G. lanceolata and G. turuturu whose highest biomass were 901.26 g·m–1 and 352.9 g·m–1, respectively. G. lanceolata that grew with higher water velocity had longer body length that could reach 142 cm. The mouthfeel of G. turuturu and G. prolongata was the worst but that of G. lanceolata and G. livida was the best. G. lanceolata and G. livida had better mouthfeel in January to March than in April. It is worth developing G. lanceolata as marine vegetable for its bigger biomass, size and its better mouthfeel.
Estimation of genetic parameters for ammonia nitrogen and freshwater tolerance traits in Penaeus monodon
Falin ZHOU, Qibing YANG, Jianghua HUANG, Shong JIANG, Lishi YANG, Tangsheng ZHANG, Shigui JIANG
Third Proofread  doi: 10.12131/20190091
[Abstract](544) [FullText HTML](166) [PDF 753KB](6)
Taking lethal time of high ammonia nitrogen and freshwater tolerance as indices, we estimated the heritability of ammonia nitrogen tolerance and freshwater tolerance of Penaeus monodon. We established 27 full-sib families including five half-sib families of P. monodon based on two breeding populations of P. monodon from Nanhai No.1 and African strain. Besides, we estimated the variance components and genetic parameters for ammonia nitrogen tolerance and freshwater tolerance by using one trait animal model and ASReml software. Then we calculated the estimated breeding values of all animals and families with best linear unbiased prediction. The heritability for ammonia nitrogen tolerance and freshwater tolerance were 0.11±0.04 and 0.29±0.08, respectively (P<0.05). The family phenotypic value correlation coefficients between ammonia nitrogen tolerance and freshwater tolerance was 0.15, showing low linear positive correlation and statistically insignificant difference. The family breeding value correlation coefficients between ammonia nitrogen tolerance and freshwater tolerance was 0.57, showing moderate linear positive correlation and statistically significant difference (P<0.01). Thus, the resistance to freshwater stress can also be improved to some extent with selection of characteristics of ammonia tolerance of P. monodon.
Effects of two breeding methods on growth and bacterial structure of Nitzschia closterium f. minutissima
Yapeng TANG, Ruixuan WANG, Jianhua HUANG, Lishi YANG, Shigui JIANG, Heizhuo LIN, Guofu WANG
Third Proofread  doi: 10.12131/20190011
[Abstract](586) [FullText HTML](161) [PDF 1254KB](2)
We compared the density, pH, dissolved oxygen and colony structure of Nitzschia closterium f. minutissima bred in negative pressure photobioreactor and open bucket, respectively. It is shown that the algae grew fast in negative pressure photobioreactor with the highest density of 1.33×107 cells·mL–1, significantly higher than that in open bucket (8.36×106 cells·mL–1). The pH in algal solution increased with increase of algal density, and there was a significant positive correlation between them (P<0.01). The highest pH values in negative pressure photobioreactor and open bucket were 10.3 and 9.3, respectively. Oppositely, in negative pressure photobioreactor, the dissolve oxygen of algea decreased with increase of algal density, which finally stabilized at about 6.5 mg·L–1. The decline of dissolved oxygen might be related to the fact that Roseobacter had become the dominant bacteria. Results of 16S rDNA gene high-throughput sequencing show that the bacterial diversity decreased significantly (P<0.05). Proteobacteria and Bacteroidetes were dominant bacteria at early stage of breeding. However, the dominant bacteria were Cyanobacteria and Roseobacter at late stage in negative pressure photobioreactor, which was obviously different from that in open bucket.
Effect of enzymatic hydrolysis from mantle of pearl oyster on skin wound healing
Faming YANG, Haisheng LIN, Xiaoming QIN, Chaohua ZHANG, Wenhong CAO, Jialong GAO
Third Proofread  doi: 10.12131/20190079
[Abstract](408) [FullText HTML](202) [PDF 889KB](9)
In order to promote the high value utilization of pearl oyster (Pinctada martensii), we were determined explore the antibacterial activity and procoagulant activity of enzymatic hydrolysis from its mantle (EHM), and the effects of EHM on open wound healing of skin of mice. Results showed that EHM possessed of procoagulant activity in mice but had no antibacterial activity against 13 tested strains. Compared with the negative control group, the healing rate of wound of mice increased significantly after skin application with EHM for 6 d (P<0.05), but there was no significant difference with comparison with the positive control group (P>0.05). The healing rate was 100% on 14th day for the drug group, and the scar contraction rate was significantly higher than that of the negative control group (P<0.05). Biochemical indicators test indicated that EHM had significant inhibitation effect on inflammatory factor IL-6 (P<0.05); compared with the negative control group, it could promote IL-10 secretion in wound tissues significantly (P<0.05), but there was no significant difference in FGF-2 content in skin tissue of the drug groups (P>0.05), and EGF content in the positive control group was significantly higher than that in the other groups (P<0.05). Howerer, there was no significant difference in the contents of FGF-2 and EGF between the drug groups (P<0.05). In summary, EHM has procoagulant, anti-inflammatory and promotional effects, which can accelerate the open wound healing of soft tissue in mice and has a certain inhibitory effect on superficial scar hyperplasia.
Diet feeding, oxygen consumption rhythm and gastrointestinal evacuation time of Trachinotus ovatus
Xinyi SUN, Xiaolin HUANG, Zhong HUANG, Xiaocong CAO, Ting ZHOU, Heizhao LIN, Hu SHU, Wei YU, Yukai YANG, Tao LI
Third Proofread  doi: 10.12131/20190072
[Abstract](591) [FullText HTML](477) [PDF 966KB](3)
In order to determine a scientific feeding strategy for Trachinotus ovatus, we investigated the day and night diet feeding, oxygen consumption rhythm and gastrointestinal evacuation time of the fish in laboratory. The diet feeding rhythm was invstigated by a continuous feeding with fixed interval (feeding once every two hours day and night for three continuous days). The oxygen consumption rhythm was measured by flow-water breathing method (measuring once every two hours day and night for 24 h). The gastrointestinal evacuation time was measured by a full feeding method (sampling once every two hours day and night for a day). Results show that T. ovatus had a daytime feeding pattern with two extremely obvious feeding peaks (10:00 and 14:00−16:00, P<0.05), and the peak periods of oxygen consumption appeared at 08:00 and 16:00, respectively (P<0.05). The stomach digesta ratio of T. ovatus decreased sharply after feeding (P<0.05), nearly 50% at 7th hour, and reached to zero after 19 h. However, the bowel digesta ratio of T. ovatus increased sharply after 1−3 hours of feeding, and reached the maximum at 11th hour and the minimum at 21st hour. Thus, it is suggested that the optimal feeding periods of T. ovatus are 09:00−10:00 and 14:00−16:00 with strong light, oxygen consumption and peak feeding. The feeding frequency is 2−3 times per day and the feeding interval is 7−9 h.
Genetic diversity analysis of Sillago japonica based on mitochondrial DNA ND2 gene
Deyu ZHENG, Yijia GUO, Tianyan YANG, Tianxiang GAO, Yao ZHENG, Donghao YUAN, Shujin SI
Third Proofread  doi: 10.12131/20190042
[Abstract](660) [FullText HTML](175) [PDF 818KB](6)
A total of 119 individuals of Sillago japonica were collected from six sampling sites (Laizhou, Jiaonan, Zhoushan, Xiamen, Shantou and Beihai). The length of 450 bp NADH dehydrogenase subunit 2 (ND2) gene fragment was amplified and sequenced. No base insertion or deletion mutations occurred and 77 mutation sites were detected, including 30 parsimony informative sites and 28 singleton polymorphic sites. Sixty-one haplotypes were defined in 119 sequences. The average haplotype diversity (Hd) and nucleotide diversity (π) were 0.945 3±0.015 5 and 0.009 718±0.005 445, respectively. The average genetic distance among the six populations was 0.008 3, and the genetic differentiation index FST value was less than 0.05, indicating no significant genetic differentiation among the populations. Analysis of molecular variance (AMOVA) shows that genetic variation of S. japonica mainly resided among individuals within populations (99.96%). The neutral tests (Tajima's D and Fu's Fs) were both negative and deviated from the neutral significantly. Besides, the nucleotide mismatches distribution showed a unimodal distribution, indicating that S. japonica had experienced population expansion in history. The estimated expansion time was about 0.12−0.29 million years ago in late Pleistocene.
Effects of desiccation and resubmersion on oxidative stress response of crayfish (Procambarus clarkii)
Haifeng WANG, Yongxu CHENG, Jinghao LI, Yewen XI, Jiayao LI
Third Proofread  doi: 10.12131/20190059
[Abstract](694) [FullText HTML](151) [PDF 1179KB](5)
In order to study the effects of desiccation stress on crayfish (Procambarus clarkii) during crayfish seedling transportation, we investigated the antioxidant stress ability and survival rate of crayfish to desiccation stress (6 h, 12 h, 18 h, 24 h) and resubmersion in water (1 h, 6 h, 12 h) at (20±1) ℃ and with (50±5)% relative humidity (RH). The results show that the desiccation time should not exceed 18 h; the mortality rate at 24th hour was 53.3%, but no juveniles died during the resubmersion. During desiccation, no significant difference was observed in total antioxidant capacity (T-AOC, P>0.05); the superoxide dismutase (SOD) significantly reduced; the catalase (CAT) activity increased with time; the malondialdehyde (MDA) content reached the maximum value after 24 h (P<0.05), and the blood sugar and muscle lactic acid increased significantly with time (P<0.05). During the resubmersion period, the SOD and CAT activities fluctuated without an obvious rule; the MDA content restored to normal level after 12 h but the T-AOC maintained a high level. The lactate contents of 6 h and 12 h groups restored to the control level after resubmersion for 1 h. The blood sugar contents of all treatment groups were always higher than that of the control group (P<0.05). It is shown that the MDA content and SOD activity which can be regarded as immune indices are more sensitive to desiccation stress. The MDA, blood sugar and lactate contents can reflect the physiology of crayfish during resubmersion period.
Physiological response of Sargassum hemiphyllum to cadmium stress
Penghao YE, Tingting HAN, Guiquan FU, Yangguang GU, Honghui HUANG
Third Proofread  doi: 10.12131/20190032
[Abstract](701) [FullText HTML](148) [PDF 850KB](5)
Sargassum hemiphyllum, a common species in coastal waters of Guangdong Province, was selected to study its physiological response to different concentrations of heavy metal (Cd2+) stress and its tolerance to Cd2+ stress in laboratory semi-static experiments, so as to provide a basis for remediation of heavy metal pollution in that area. The results show that chlorophyll a (Chl-a), carotenoid (Car), soluble protein (SP), soluble sugar (SS) and antioxidant enzyme activity (SOD and CAT) of S. hemiphyllum at Cd2+ concentration of 0.1 mg∙L−1 had no significant difference with the control (P>0.05). The contents of Chl-a, Car, SP, SS, SOD and CAT at ρ(Cd2+) of 0.5 ~12.5 mg∙L−1, were significantly higher than those of the control (P<0.05); there was no significant change in MDA contents under Cd2+ concentration of 0.1~0.5 mg∙L−1 (P>0.05), and significant increase at Cd2+ concentration of 2.5~12.5 mg∙L−1 (P<0.05). Therefore, S. hemiphyllum had stronger stress resistance at Cd2+ concentration of ≤0.5 mg∙L−1, while excessive Cd2+ stress of >0.5 mg∙L−1 will be harmful for its photosynthesis and antioxidant function.
Water quality evaluation of Pearl River Delta based on environmental factors and phytoplankton
Xin LI, Zini LAI, Wanling YANG, Chao WANG
Third Proofread  doi: 10.12131/20190020
[Abstract](689) [FullText HTML](184) [PDF 1125KB](14)
In order to select asuitable method for water quality evaluation in the Pearl River Delta (PRD), we accessed and analyzed the water environment factors and phytoplankton data in PRD in 2015. Four phytoplankton indices, including Shannon index, evenness index, richness index and biomass index, were selected from six common phytoplankton indices based on similarities by using self-organizing map (SOM). Then, we compared the water quality evaluation results of the above indices and environmental factors. The results based on dissolved oxygen and ammonia nitrogen could reflect the spatial differences between city centers and other regions, but total nitrogen and total phosphorus were not suitable for water quality evaluation. However, the results based on Shannon and biomass indices could reflect the differences between city centers and other regions, but evenness and richness indices were not suitable for water quality evaluation. Except for total nitrogen and total phosphorus, the evaluation results of other environmental factors and four phytoplankton indices show that the water quality of the survey area was generally good, but the water quality of stations around the city was slightly poor. Thus, issolved oxygen, ammonia nitrogen, Shannon index and biomass index are suitable environmental factors and phytoplankton index for water quality evaluation.
Study on carbon and nitrogen stable isotopes of main fishery species in typical gulf, southern China
Wenbo ZHANG, Honghui HUANG, Chunhou LI, Yong LIU, Zhanhui QI, Shannan XU, Huaxue LIU
Third Proofread  doi: 10.12131/20180173
[Abstract](507) [FullText HTML](167) [PDF 859KB](9)
In order to understand the characteristics of trophic structure of main fishery in typical gulf of southernh China with significant habitat difference, we analyzed the ratio of carbon and nitrogen stable isotopes (δ13C and δ15N) of major fishery species collected in Hailing Bay and Lingshui Bay in wet season of 2015, and calculated several quantitative metrics based on the δ13C and δ15N ratios so as to quantitatively characterize the trophic structure in community-wide aspect. The results show that the average δ13C [−15.36±0.62)‰] and δ15N [(15.53±0.94)‰] values of main fishery species in Hailing Bay were significantly higher than those in Lingshui Bay [(−17.44±1.21)‰ and (13.78±1.31)‰, P<0.01]. However, the NR and TA values of Hailing Bay were lower than those of Lingshui Bay, showing longer food chain length and higher diversity in Lingshui Bay. Calculated by 3.4‰ as a nutrient grade of nitrogen stabilized isotope enrichment, the grade distance of Lingshui Bay fishery was only 1.37, lower than 1 of Hailing Bay, indicating that both Lingshui Bay and Hailing Bay have relatively less high trophic organisms and the food webs are often disturbed.
Difference analysis of trace elements in statolith of Sthenoteuthis oualaniensis in South China Sea
Yu LIU, Xuehui WANG, Feiyan DU, Bilin LIU, Peng ZHANG, Mengna LIU, Yongsong QIU
Third Proofread  doi: 10.12131/20190039
[Abstract](595) [FullText HTML](163) [PDF 1425KB](19)
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to measure the concentration of trace elements in the otolith of the South China Sea squid (Sthenoteuthis oualaniensis). The composition of trace elements in the otolith and the change of the ratio of trace elements to calcium (Ca) were analyzed. The differences and the relationship between the otolith and habitat were discussed. The results show that the main trace elements are Ca, Sr, Na, Fe, Ba and Mn. Analysis of variance (ANOVA) reveals no significant difference between populations and genders (P>0.05). There was significant difference in the ratio of trace elements to calcium among different regions of statolith (P<0.01) except for Fe/Ca. The Sr/Ca ratio was the highest in the nucleus and then decreased. There was no significant difference in Sr/Ca ratios among different spawning groups and geographical regions (P>0.05). There was a positive relationship between Sr/Ca and temperature, and a negative relationship with salinity at the larval stage. Sr/Ca can be used as a good temperature indicator. Na/Ca first increased and then decreased, highest at the dark zone. Na/Ca is significantly different among different spawning populations at the nuclear and post nuclear zones (P<0.01). Mn/Ca and Ba/Ca, which first decreased and then increased (lowest in the dark region), increased at the edge zone and peripheral zone. There was a positive relationship between Ba/Ca and salinity at adult stage, and Ba/Ca can be used as an indicator of vertical movement. Fe/Ca was significantly different among different spawning populations and geographic areas (P<0.01). It is shown that Na/Ca and Fe/Ca are suitable for distinguish of different groups of squid, and Sr/Ca and Ba/Ca can be used to estimate the habitat environment of squids in the South China Sea.
Evaluation on carrying capacity of fishery resources in coastal waters of Dapeng Peninsula, Shenzhen
Xinling LONG, Pimao CHEN, Huarong YUAN, Xue FENG, Jing YU, Liming SHU, Xiaoguo LI, Wenjing CHEN, Zicong CHEN
Second Proofread  doi: 10.12131/20190024
[Abstract](733) [FullText HTML](171) [PDF 1073KB](8)
To explore the carrying capacity of fishery resources in the coastal waters of Dapeng Peninsula, Shenzhen, in consideration of the actual situation of that sea area, we established an evaluation index system by referring to the Resource and Environmental Carrying Capacity Monitoring and Early Warning Technology Method (Trial) and the evaluation methods of fishery resources carrying capacity at home and abroad. Based on the survey data of fishery resources in that waters every autumn in 2012 to 2016, we applied two methods [comparing the data between 2016 and the previous three years (2013 to 2015) and comparing the data between 2016 and the previous four years (2012 to 2015)] to evaluate the carrying capacity. The results of both methods show that the swimming animal index had a downward trend. The fish spawn and larvae index decreased significantly. The fishery resources carrying capacity was almost overloaded. Therefore, it is recommended to strengthen the monitoring and investigation of fishery resources as well as the evaluation and early warning of fishery resource carrying capacity, so as to provide technical support for promoting the restoration and protection of fishery resources as well as proliferative maintenance.
Optimization of multi-enzymatic extraction of polysaccharide from Gelidium amansii by response surface methodology
Ruonan PEI, Honglei ZHAI, Bo QI, Xianqing YANG
Second Proofread  doi: 10.12131/20190081
[Abstract](501) [FullText HTML](146) [PDF 1768KB](4)
To optimize the multi-enzymatic extraction process of polysaccharides from Gelidium amansii, we designed a three-factor and three-level Box-Benhnken center-united experiment based on single factor test, and conducted a regression analysis. The optimum technological parameters of enzymatic extraction of G. amansii polysaccharide were: enzymes addition 2.30%, enzymatic hydrolysis temperature 60.43 ℃, ratio of material to water 1∶32 (g·mL−1). The extraction yield of polysaccharide was up to 15.98% after 120 min of enzymatic hydrolysis under these conditions.
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Research Paper
2019, 15(4).  
[Abstract](373) [PDF 3099KB](10)
Analysis of community structure and diversity of nekton in Kaozhouyang Bay using gill nets and cages
Rui YING, Li JIANG, Fangmin YIN, Jianrong HUANG, Zufu LI, Yingyong WANG, Jianxiang FENG
2019, 15(4): 1-10.   doi: 10.12131/20190009
[Abstract](2039) [FullText HTML](973) [PDF 1007KB](33)
To better understand the status of fishery resource of Kaozhouyang Bay, we have conducted a seasonal investigation of the community structure and diversity of the nekton by using gill nets and cages net from November 2017 to July 2018. A total of 93 economic species were collected, and among them 61 were fish belonging to 11 orders and 33 families, accounting for 64.52% of the total species number, and the rest were crustaceans. Perciformes (45.16%) and Clupeiformes (7.52%) which were mostly warm water species were the two largest orders of fish. The catches had significant seasonal variation (summer>spring>autumn>winter), and mostly fell in two intervals of 0−8 g and 8−64 g. The diversity indices in Kaozhouyang Bay showed obvious variation. The species richness index was 0.81−3.63; the Shannon-Wiener index was 0.81−2.03; the evenness index was 0.55−1.69. No significant difference was found in the richness index, Shannon-Wiener index and evenness index among different seasons and stations. In conclusion, the total fishery resources in Kaozhouyang Bay are relatively small. The biodiversity shows obvious seasonal variation, while the spatial variation is insignificant.
Change in planktonic algae community in scallop culture area of Laizhou Bay during 2015 to 2017
Xilei LI, Xiao YU, Yubo LU, Junli YANG, Longbo CUI
2019, 15(4): 11-18.   doi: 10.12131/20180254
[Abstract](1467) [FullText HTML](477) [PDF 733KB](18)
According to the water quality survey data collected from the scallop culture area in Zhaoyuan coastal waters of Laizhou Bay from May to November during 2015−2017, we analyzed the spatial distribution, community structure and interannual variation characteristics of phytoplankton. The study identified 138 species of phytoplankton, among which 86 species were Bacillariophyta, that was dominant in respects of both quantity and species composition. The phytoplankton density, biodiversity index and evenness index showed obvious seasonal characteristics. Phytoplankton density were the highest in May−June and September−October. The biodiversity index ranged from 1.92−3.57, and the evenness index variation ranged from 0.44−0.87. Phytoplankton was mainly in temperate coastal ecological type and the community structure presented temperate floristic characteristics of sea area. There were many species of phytoplankton which distributed rather evenly, and the community structure was relatively stable.
Ecological carrying capacity of six species of stock enhancement in Pearl River estuary based on Ecopath model
Yan LIU, Zhongxin WU, Changping YANG, Binbin SHAN, Shengnan LIU, Dianrong SUN
2019, 15(4): 19-28.   doi: 10.12131/20180265
[Abstract](860) [FullText HTML](435) [PDF 822KB](22)
Stock enhancement is important for conservation of exploitable resources. Assessment of ecological capacity of the discharged sea area before discharge and planned implementation of proliferation and discharge activities can avoid damage to the original ecosystem. Based on the survey data of the fishery resources of Pearl River estuary in 2016, an Ecopath mass-balance model of the Pearl River estuary ecosystem consisting of 29 functional groups was constructed. Thus, the overall characteristics of the ecosystem, the food-web structure and the mixed trophic impact were analyzed. The ecological carrying capacities of six species of stock enhancement which were suitable for this area were estimated. The results show that the fractional trophic levels ranged from 1 to 4.2, and those of the six species ranged from 2.2 to 3.7, with marine mammals occupying the highest trophic level. The total system throughput of the ecosystem was 9 092.447 t·(km2·a)–1, and the total energy transfer efficiency was 12.23%. The connectance index and system omnivory index were 0.370 and 0.287, respectively. There were two main channels of food chain in the ecsystem, and the energy flow was dominated by grazing food chain. The ecological carrying capacities of biomass for Lateolabrax japonicus, Acanthopagrus schlegelii, A. latus, Penaeus penicillatus, P. monodon and Paphia undulata were 0.094 t·km–2, 0.500 t·km–2, 0.650 t·km–2, 1.580 t·km–2, 1.610 t·km–2 and 75.870 t·km–2, respectively.
Influence of mariculure on tempo-spatial distribution of nitrogen and phosphorus in subtropical zone: a case study of Shen'ao Bay
Shumin XU, Zhanhui QI, Rongjun SHI, Yong LIU, Tingting HAN, Honghui HUANG
2019, 15(4): 29-38.   doi: 10.12131/20190049
[Abstract](1170) [FullText HTML](433) [PDF 905KB](30)
We investigated the tempo-spatial variation of disovled inorganic nitrogen (DIN) and phosphate (PO4-P) in Shen'ao Bay that is a typical subtropical aquaculture bay. Besides, we studied the effects of large-scale aquaculture activities such as fish cage and shellfish raft on the tempo-spatial distribution of nutrients, and evaluated the potential limiting factors of the nutrients. The concentration and distribution of DIN and PO4-P showed obvious seasonal variation (DIN and PO4-P reached their maximum values in autumn and winter, respectively, and both reached their minimum values in summer). The DIN nutrients concentrations and N/P ratios in fish cage area in spring were lower than those in oyster-macroalgae culture area and the control area. However, in the other three seasons, the DIN and PO4-P concentrations and N/P ratios in fish cage area were higher than those in the other areas. There was no significant difference in the nitrogen and phosphorus concentrations as well as N/P ratios between oyster-macroalgae culture area and the control area in each season. Both DIN and PO4-P were higher than the theoretical threshold for phytoplankton growth, indicating that there was no absolute nutrient limitation. The N/P ratios in summer and winter were 13.6 and 13.1, respectively, which were lower than the Redfield ratio, indicating that there was potential N limitation during these seasons. The N/P ratios in spring and autumn were 16.6 and 19.0, respectively, indicating potential P limitation. The average seasonal ratio was 14.3, indicating that N was probably the most limiting nutrient in Shen'ao Bay. DIN was dominated by nitrate nitrogen (NO3-N) except for summer with percentages of 51.7%−92.7%, followed by ammonia nitrogen (NH4-N) with percentages of 5.2%−43.8%, and nitrite nitrogen (NO2-N) was lowest with percentages of 2.1%−27.2%, indicating that the thermodynamic equilibrium of N was reached. Compared with 2001, the concentrations of both DIN and PO4-P decreased, with the trophic level changing into poor from moderate. It is shown that the productivity level of Shen'ao Bay is still controlled by nitrogen, and the tempo-spatial distribution of nutrients reflects the impact of large-scale shellfish culture to a certain extent.
Domestication and cultivation of nitrifying bio-floc
Daohe TIAN, Fukun GUI, Hua LI, Ziming ZHOU, Qingsong LIU, Hongbiao DONG, Yafei DUAN, Jiasong ZHANG
2019, 15(4): 39-45.   doi: 10.12131/20180260
[Abstract](1402) [FullText HTML](598) [PDF 839KB](11)
In this study, nitrifying biofloc was cultivated from sewage outlet sediment by gradually reducing carbon source so as to improve its nitrogen removal performance, reduce the cost and shorten the culture period. High throughput sequencing technology was used to analyze the bacterial community structure of the seed sludge and nitrifying biofloc. The results show that the main dominant flora of seed sludge was consistent with other reported heterotrophic flocs, indicating that the sewage outlet sediment has good microbial flora foundation and can form nitrogen removal stable biofloc within 7 d. As the decrease of carbon source, the microbial flora structure of heterotrophic biofloc changed, and the nitrifying biofloc gradually formed after 32-day target training. The dominant bacterial communities of the seed sludge and nitrifying biofloc were Proteobacteria and Bacteroidetes. At Class level, the dominant flora of seed sludge were Gammaproteobacteria, Bacteroidia and Deltaproteobacteria, while the dominant flora of nitrifying biofloc were Bacteroidia, Gammaproteobacteria and Anerolineae. Among them, the total relative abundance of nitrifying bacteria in nitrifying biofloc had greatly increased compared with the seed sludge. The nitrifying biofloc contributes to high nitrogen removal performance and less aquaculture cost.
Effects of periodic hypoxia stress on intestinal microflora structure of Lateolabrax maculatus
Yongxu SUN, Hongbiao DONG, Wenhao WANG, Ming CAO, Yafei DUAN, Hua LI, Qingsong LIU, Jiasong ZHANG
2019, 15(4): 46-52.   doi: 10.12131/20190021
[Abstract](1210) [FullText HTML](366) [PDF 1335KB](13)
Based on the technology of Illumina MiSeq high throughput sequencing, we analyzed the effects of periodic hypoxia stress on intestinal microflora structure of Lateolabrax maculatus, so as to provide references for the study of the adaptation mechanism of intestinal flora of the juveniles to environmental hypoxia. The results show that hypoxia caused a significant increase in the diversity and richness of intestinal microflora (P<0.05). The species richness was rather different between the two groups. The operational taxonomic units (OTUs) of hypoxic group were significantly more than those of normoxic group (P<0.05). At the level of Class classification, the dominant bacteria of both groups were Proteobacteria, Firmicutes and Bacteroidetes. Compared with the normoxic group, the relative abundance of Proteobacteria decreased significantly in hypoxic group, while that of Bacteroidetes increased significantly (P<0.05). At the level of Genus classification, the relative abundance of Alphaproteobacteria and Bacilli in hypoxic group decreased significantly, while those of Clostridia, Gammaproteobacteria and Bacteroidia increased significantly (P<0.05). Periodic hypoxia stress also led to an increase of relative abundance of anaerobes or facultative anaerobes (Anaerolineaceae, Lachnospiraceae and Ruminococcaceae) and oxygen-producing bacteria (Chlorobiaceae) in the intestine of L. maculatus.
Effects of dietary carbohydrate to lipid ratio on growth performance, body composition and serum biochemical indices of adult GIFT Oreochromis niloticus
Fan WU, Ming JIANG, Hua WEN, Wei LIU, Juan TIAN, Lijuan YU, Xing LU
2019, 15(4): 53-60.   doi: 10.12131/20190047
[Abstract](1517) [FullText HTML](415) [PDF 820KB](11)
To determine the optimal dietary carbohydrate to lipid (C/L) ratio for GIFT Oreochromis niloticus, we formulated six isonitrogenous and isoenergetic diets with C/L ratios of 1.53, 2.36, 3.55, 5.58, 9.85 and 21.82, respectively. Each diet had been randomly fed to the fish with initial average body mass of (218.33±11.03) g for 56 d. The weight gain rate (WGR) and specific growth rate (SGR) were the highest in group of 3.55, significantly higher than those in groups of 1.53, 9.85 and 21.82 (P<0.05). The feed efficiency (FE) and protein efficiency ratio (PER) in groups of 2.36−5.58 had insignificant difference, but were significantly higher than those in groups of 1.53 and 21.82. The viscerosomatic index (VSI) and hepatosomatic index (HSI) decreased significantly as the dietary C/L ratios increased (P<0.05), but the survival rate (SR) showed insignificant difference among different treatments (P>0.05). The whole body and liver lipid content decreased significantly as C/L ratios increased (P<0.05). The serum triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels decreased as dietary C/L ratios increased, whereas the low-density lipoprotein cholesterol (LDL-C) and glucose (GLU) contents showed an opposite trend (P<0.05). Based on the second-order polynomial regression analysis of WGR, PER and FE against dietary carbohydrate and lipid levels, the optimal C/L ratios were 4.19, 4.15 and 4.11, respectively. In conclusion, the diet with C/L ratio of 4.11−4.19 is optimal for adult GIFT O. niloticus.
Vitamin D3 requirement of grouper (Epinephelus coioides) in practical diet
Shiwei XIE, Lixia TIAN, Yongjian LIU, Haitao ZHANG, Jin NIU, Jianjun LIANG, Weiping FANG, Jicai SU
2019, 15(4): 61-67.   doi: 10.12131/20190029
[Abstract](1501) [FullText HTML](460) [PDF 569KB](7)
Six isonitrogenous and isoenergetic diets supplemented with different levels of vitamin D3 (0, 1 000 IU·kg−1, 2 000 IU·kg−1, 4 000 IU·kg−1, 8 000 IU·kg−1, 100 000 IU·kg−1) were formulated to evaluate the requirement of vitamin D3 to Epinephelus coioides, namely Diet 1, Diet 2, Diet 3, Diet 4, Diet 5 and Diet 6. Diet 3 obtained higher weight gain rate, specific growth rate and feed efficiency than the other groups (P<0.05). With dietary supplemental vitamin D3 higher than 2 000 IU·kg−1, the intraperitoneal fat ratio (IPF) and viscerosomatic index (VSI) decreased significantly with increasing dietary vitamin D3 levels (P<0.05). The protein contents in whole body and muscle decreased with increasing dietary vitamin D3 levels (P<0.05), but the lipid and ash contents showed no difference in whole body and muscle among all the groups. When the dietary supplemental vitamin D3 was lower than 2 000 IU·kg−1, the calcium (Ca) and phosphorus (P) contents in fish bone were positively correlated with the vitamin D3 levels. Based on Ca and P contents in bones, the optimal supplementation level of vitamin D3 in practical diet should be 2 000 IU·kg−1.
Effects of substitution of fish meal by fermented soybean meal on growth and serum biochemistry of golden pompano (Trachinotus ovatus)
Xiuling LI, Baosuo LIU, Nan ZHANG, Liang GUO, Shigui JIANG, Dianchang ZHANG
2019, 15(4): 68-75.   doi: 10.12131/20190041
[Abstract](1445) [FullText HTML](407) [PDF 722KB](12)
To investigate the effects of substitution of fish meal by fermented soybean meal on the growth performance and serum biochemistry of Trachinotus ovatus, we have formulated five experimental diets, adding 0% (FM), 25% (FSM25), 50% (FSM50), 75% (FSM75) and 100% (FSM100) fermented soybean meal to replace fish meal. In order to eliminate the effects of limiting amino acids, we added 0%, 0.10%, 0.22%, 0.35% and 0.45% lysine, as well as 0%, 0.14%, 0.27%, 0.41% and 0.54% methionine, respectively. The results show that the weight again rate, specific gain rate, specific growth rate and feed intake did not have significant difference among FSM25, FSM50 and FM groups (P>0.05), but the feed conversion ratio in FSM100 group was significantly higher than that in FM group (P<0.05). There was insignificant difference in the muscle moisture, ash, crude protein, crude fat contents between the fermented soybean meal groups and FM group (P>0.05). The serum aspartate aminotransferase (AST) activities and total protein (TP) contents in FSM75 and FSM100 groups were significantly higher and lower than those in FM group, respectively (P<0.05). The activities of alanine aminotransferase (ALT) and superoxide dismutase (SOD) in FM100 group were significantly higher than those in FM group, respectively (P<0.05). The relative expressions of IGF-1 and GH genes in FSM75 and FSM100 groups were significantly lower than those in FM group (P<0.05). In summary, by adding limiting amino acids, the substitution of fish meal by fermented soybean meal not exceeding 50% does not have adverse affects on T. ovatus. According to the regression curve, the substitution level of 17.5% will achieve the best effects.
Study on selection and spatial distribution of two kinds of caverns for Procambarus clarkii
Lei LUO, Jianhua HUANG, Dongliang LIU, Liqi TAN, Shigui JIANG, Falin ZHOU, Song JIANG, Qibin YANG, Lishi YANG
2019, 15(4): 76-81.   doi: 10.12131/20190005
[Abstract](1327) [FullText HTML](482) [PDF 719KB](23)
We investigated the selection adaptability and spatial distribution ratio, distribution of sex ratio inside or outside different caves, as well as the quantity and sex ratio in single cave of Procambarus clarkii in two kinds of caves (staked bamboo tube and PVC tube) during artificial breeding. The results show that P. clarkii tended to hide in caves (Group A: 83.47%, Group B: 89.87%), especially in bamboo cave [Group B: bamboo tube (71.80%) and PVC tube (11.63%)]. Vertical placement of the cave will affect the distribution of P. clarkii which prefered to hide in the caves at middle and lower layers as well at lower layer, and the quantity reduced from bottom to top. P.clarkii had a phenomenon of polygyny cohabitation, but the laws of male and female distribution in different vertical spaces were not obvious, with the highest ratio of male and female in the lowerest layer of Group A (3.43:1) and the uppermost layer of Group B bamboo cave (2.86:1).
A preliminary study on relationship between eyestalk and growth of Charybdis japonica in offshore waters of Jiangsu
Huimin FENG, Yuwei LU, Hui HU, Zhenyu NI, Jian ZHANG
2019, 15(4): 82-87.   doi: 10.12131/20180271
[Abstract](1206) [FullText HTML](400) [PDF 852KB](11)
We collected 57 individuals of Charybdis japonica from the offshore waters of Nantong, Jiangsu Province, China to analyze their eyestalk microstructure, explore their age and growth, and establish a corresponding growth model. The results show that the eyestalk microstructure of C. japonica consists of four parts: epicuticle, exocuticle, endocuticle and menbranous. The growth lines that can be used for research mainly exist in endocuticle. By analyzing the biological data and growth pattern, in addition to application of AIC method, we found that in seven commonly used growth functions, a linear function relationship is presented between carapace length and carapace width, and a power function relationship is presented among carapace length, carapace width and body mass. However, the relationship among growth lines and carapace length, carapace width as well as body mass is expressed by logistic function relationship.
Cloning, expression analysis of TRIAP1 and its related miRNAs screening in Penaeus monodon
Enrui LIU, Chao ZHAO, Pengfei WANG, Sigang FAN, Lulu YAN, Lihua QIU
2019, 15(4): 88-98.   doi: 10.12131/20180285
[Abstract](1073) [FullText HTML](383) [PDF 2251KB](10)
TRIAP1 can participate in vivo responses by inhibiting apoptosis. In order to analyze the expression regulation of TRIAP1 and miRNAs that regulate TRIAP1's expression under Vibrio harveyi challenge in Penaeus monodon, we obtained the P. monodon TRIAP1 gene (PmTRIAP1) cDNA by RACE, then detected the tissue distribution of PmTRIAP1 by quantitative real-time PCR (qRT-PCR), and investigated the expression association between PmTRIAP1 and its related miRNAs under V. harveyi challenge. The results show that the full-length PmTRIAP1 cDNA sequence was 2 522 bp, containing an 11 bp 5' non-coding region (UTR), a 2 289 bp 3'-UTR and a 222 bp open reading frame encoding 73 amino acids. The qRT-PCR analysis shows that PmTRIAP1 was ubiquitously expressed in all the tested tissues and the highest expression level was obtained in hemocyte. The expression of PmTRIAP1 decreased significantly; however, the expressions of Pm-miR-145-3p and Pm-miR-454-3p increased significantly under V. harveyi challenge, which suggests that the expression levels of PmTRIAP1 and Pm-miR-145-3p, Pm-miR-454-3p were negatively correlated. Dual luciferase reporter assay shows that Pm-miR-145-3p and Pm-miR-454-3p can bind PmTRIAP1 3'UTR to reduce luciferase activity. It is suggested that both Pm-miR-145-3p and Pm-miR-454-3p can target regulate the expression of PmTRIAP1.
Cloning and starvation response of mc5r gene in Spinibarbus hollandi
Huiqiang ZHOU, Kailing CHEN, Hu SHU, Yang YANG, Dongming ZHONG, Mingqing ZHANG
2019, 15(4): 99-106.   doi: 10.12131/20190027
[Abstract](750) [FullText HTML](273) [PDF 1639KB](16)
In this study, melanocortin receptor-5 (mc5r) gene of Spinibarbus hollandi was cloned by homology cloning and genome walking method. Bioinformatics methods were used to analyze the gene sequence and deduced amino acid sequence of mc5r. The tissue distribution, diurnal change and starvation response of mRNA expression were detected by real-time PCR. The full length of mc5r gene was 1 947 bp with one exon of 987 bp encoding 329 amino acids. According to multiple sequences alignment and phylogeny evolution analysis, the homology of S. hollandi mc5r amino acid sequence with Cyprinus carpio and Sinocyclocheilus rhinocerous reached 98%. S. hollandi mc5r had significant expression in brain, followed by diencephalon and heart, relatively less in mesencephalon and cerebellum, and weak in kidneys, stomach, muscles, spleen, intestines, gonadal, liver, medulla oblongata and eye. The diurnal periodicity expression of mc5r mRNA changed with day and night regularly. In the starvation refeeding experiment, the expression of refeeding fish increased significantly after starvation, but then decreased. It is indicated that mc5r may have some effects on food intake regulation.
Study on non-CO color retention method of tilapia fillets
Min ZHAO, Laihao LI, Xianqing YANG, Hui HUANG, Ya WEI, Jianwei CEN, Zhi LIN
2019, 15(4): 107-112.   doi: 10.12131/20180227
[Abstract](816) [FullText HTML](311) [PDF 1826KB](11)
In order to study new non-CO color retention method of tilapia fillets and achieve a safe and effective color retention process, we used color difference value as main evaluation index for the fillets' color. Based on single-factor test of sodium nitrite concentration, sodium bicarbonate concentration and soaking time, we used Box-Behnken center design principle to optimize the response surface test of the assay scheme. The results show that soaking in a composite solution of sodium nitrite concentration of 0.4 g·L−1 and sodium bicarbonate concentration of 5.0 g·L−1 for 22 min performs well. The redness value (Δa*) of the red meat was 1.97 with an increase of 17.35%. The overall color of the fillets was improved. A new method of non-CO color retention technology of tilapia fillets is obtained.
Comparative analysis of nutritional components of several roes
Shuang MA, Shuxian HAO, Laihao LI, Xianqing YANG, Hui HUANG, Ya WEI, Jianwei CEN, Honglei ZHAI
2019, 15(4): 113-121.   doi: 10.12131/20180266
[Abstract](1158) [FullText HTML](406) [PDF 657KB](9)
In order to analyze the nutrition characteristics of different kinds of roes, we determined the proximate composition, amino acids, fatty acids and mineral elements of roes of Salmon solar, Exocoetidae cypselurus, Pseudosciaena crocea, Acipenser baeri, A. gueldenstaedti, A. schrenckii and Huso dauricus. The results show that E. cypselurus roe had the highest moisture content (813.1 g·kg–1), lowest ash content (16.0 g·kg–1) and lowest crude protein content (133.5 g·kg–1). A. schrenckii roe had the highest crude protein content (281.5 g·kg–1) and crude fat content (166.3 g·kg–1), and S. solar roe have the lowest crude fat content (54.9 g·kg–1). The contents of total amino acids (27.67%) and delicious amino acids (9.31%) in A. gueldenstaedti roe were the highest. The amino acid score (AAS) of the seven kinds of roes were higher than the FAO/WTO standard except tryptophan, and the ratio of essential amino acids to total amino acids ranged from 41.34% to 43.89%. The contents of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) in seven kinds of roes were 25.83%−35.41%, 21.39%−26.65% and 41.84%−47.77%, respectively, and the total amount of EPA+DHA ranged from 20.06% to 40.59%. The roes contain high contents of phosphorus (P), iron (Fe) and zinc (Zn). Thus, the roes of the seven species are rich in various nutrients. According to the contents of crude fat and unsaturated fatty acid as well as amino acid evaluation, the nutritional values of four sturgeon roes are better than those of the other three kinds of roes.
Protection of Jian carp with immunization of CyHV-3 ORF65 DNA vaccine
Ying LI, Zhenxing LIU, Yanping MA, Junming CAO, Jiangyao MA, Le HAO, Zhiling LIANG, Hao KE, Yugu LI
2019, 15(4): 122-126.   doi: 10.12131/20190033
[Abstract](872) [FullText HTML](268) [PDF 895KB](7)
In order to develop a DNA vaccine against Cyprinid herpes virus 3 (CyHV-3), also known as Koi herpesvirus (KHV), we inserted CyHV-3 ORF65 into pEGFP-N1 to construct recombinant plasmid pEGFP-ORF65. The expression of pORF65-EGFP fusion protein in Cyprinus carpio var. Jian was confirmed by transfection and in vivo imaging experiments. The recombinant plasmid was injected into the tail stalk of the carp seedlings at dosage of 3 μg·tail−1 for about 10 g and immunized for three times. ELISA detection shows that pEGFP-ORF65 could significantly increase the level of serum specific antibodies. The challenge test shows that 21 d after CyHV-3 challenge, the survival rates of PBS group, pEGFP-N1 group and pEGFP-ORF65 group were 25%, 30% and 90%, respectively, which significantly improved the survival rate of the carp seedlings (P<0.01). The study provides a basis for the application of ORF65 as a target gene of DNA vaccine in the prevention and control of CyHV-3.
Analysis of genetic diversity of Bahaba flavolabiata based on microsatellite markers
Yanhua ZHAO, Youjun OU, Jiufu WEN, Jia'er LI, Hui ZHOU
2019, 15(4): 127-132.   doi: 10.12131/20180261
[Abstract](1498) [FullText HTML](487) [PDF 778KB](20)
We examined the genetic diversity of 19 Bahaba flavolabiata samples collected from the Pearl River estuary based on microsatellite markers, so as to provide references for the identification of its germplasm resources and future breeding. The results show that the number of alleles (Na) in each of the 29 microsatellite loci was 2−7, with a total number of 121 alleles. The average number of alleles in each locus was 4.17. The effective number of alleles (Ne) was 1.060 6−6.056 1, with a sum of 85.205 0. The average values of the observed heterozygosity (Ho) and the expected heterozygosity (He) were 0.659 3 and 0.597 3, respectively. The value of polymorphism information content (PIC) was 0.055 5−0.813 7, with an average of 0.542 3, and 19 loci showed high polymorphism. Five loci deviated significantly from the Hardy-Weinberg equilibrium (corrected P≤0.036). The allelic richness (Rs) was 2−6.976, with a sum of 119.638. The genetic diversity (GD) was 0.059−0.856. It is suggested that most of the SSR loci developed in this study are highly polymorphic, and the genetic diversity of B. flavolabiata population is at a higher level.
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Zooplankton community structure in Hailing Bay and its relationship with primary environmental factors
Yuyan GONG, Yayuan XIAO, Shannan XU, Yong LIU, Yutao YANG, Zirong HUANG, Chunhou LI
Latest Accepted  doi: 10.12131/20180220
[Abstract](186) [FullText HTML](91)
Based on the data obtained from four voyages in February (winter), July (summer), November (autumn) in 2015 and April (spring) in 2016, we investigated the structure of zooplankton community, including species composition, abundance, biomass, dominant species and species diversity in Hailing Bay. A total of 132 zooplankton species and 14 types of pelagic larvae were identified. The most dominant group of zooplankton was Copepoda (54 species). There was no similar dominant species between two adjacent seasons, indicating that the zooplankton community in Hailing Bay had obvious seasonal variation. Abundance and biomass of zooplankton were highest in winter but lowest in summer. Zooplankton abundance was greater in autumn and spring than in winter and summer except for Noctiluca scintillans. Both Shannon-Wiener diversity index (H′) and Pielou's evenness index (J′) were higher in autumn and summer than in winter and spring. N. scintillans appeared in winter and spring with mass propagation since the temperature was low, but disappeared in summer and autumn. Correlation analysis shows that there is a significant negative correlation between N. scintillans-dominated Protozoa and water temperature, indicating that water temperature is one of the main factors affecting the growth and reproduction of N. scintillans in Hailing Bay.
Relationship of hepatopancreas colours with lipid and mineral contents in cultured grass carp during winter
Chunhong HUANG, Jiali LI, Yanju LEI, Zhongguo XIE
Latest Accepted  doi: 10.12131/20190073
[Abstract](403) [FullText HTML](145)
To clarify the relationship between hepatopancreas colours and its lipid and mineral contents of grass carp (Ctenopharyngodon idella), we analyzed the moisture, total lipid and minerals contents of hepatopancreas with different colours during winter. Results show that the average moisture and lipid contents in kermesinus, spot, white and yellow hepatopancreas were 77.78%, 70.98%, 67.91%, 64.01% and 2.06%, 2.85%, 4.24%, 5.28%, respectively, which were significantly different (P<0.05). Compared with kermesinus hepatopancreas, the Ca, Cr, Zn and Se in spot, white and yellow hepatopancreas were all increased significantly (P<0.05). Cu and As in spot hepatopancreas, and Mg, Fe, Cu in white hepatopancreas were lower than those in kermesinus hepatopancreas. However, all the detected minerals in yellow hepatopancreas were higher than those in kermesinus hepatopancreas. Briefly, there was less lipid in hepatopancreas of grass carp during winter, but when the hepatopancreas colours changed from kermesinus to spot, white and yellow, the moisture gradually decreased but the lipid gradually increased. Compared with kermesinus hepatopancreas that had lower lipid content, the contents of Ca, Cr, Zn and Se in hepatopancreas with the other colours which had higher lipid contents significantly increased (P<0.05).
Effect of precooling before slaughter on quality of Micropterus salmoides during ice storage
Ya WEI, Hui HUANG, Laihao LI, Xianqing YANG, Honglei ZHAI, Wanling LIN, Shuxian HAO
Latest Accepted  doi: 10.12131/20190003
[Abstract](442) [FullText HTML](154)
In order to investigate the effect of precooling before slaughter on the quality of fish fillets during ice storage, we treated fresh Micropterus salmoides at different precooling temperatures (15 ℃, 10 ℃ and 5 ℃) for 0.5 h, and then killed and preserved them in ice. The physicochemical [pH, TVB-N, K value and TBA)] and microbial (TVC) indices were measured on 0th, 3rd, 6th, 9th, 12th, 15th, 18th and 21st day, respectively. The results indicate that precooling treatment at 15 ℃ could better retain the quality of M. salmoides during ice storage and stabilize the sensory quality of its muscle. Besides, it could inhibit the growth of bacteria and the increase of TVB-N, K value and TBA. The precooling extended the shelf life of M. salmoides fillets up to 3 d during ice storage compared with the control group.
Molecular characterization and expression pattern analysis of a defensin (HdDef1) from small abalone (Haliotis diversicolor)
Tuo YAO, Jie LU, Lingtong YE, Huasheng CHEN, Jiangyong WANG
Latest Accepted  doi: 10.12131/20190045
[Abstract](206) [FullText HTML](98)
Defensin is one of the most important antimicrobial peptides (AMPs) that participates in invertebrate innate immunity against invading pathogens. In the present study, a novel defensin was identified in small Haliotis diversicolor (denoted as HdDef1) using RNA-seq and RACE techniques. The HdDef1 cDNA contained a 201 bp open reading frame (ORF) encoding 66 amino acids, a signal peptide of 18 amino acids and a mature peptide of 48 amino acids. The mature peptide of HdDef1 shared common features of AMPs, such as lower molecular mass, net positive charge (+1) and a high hydrophobic residue ratio (45%). In addition, six cysteines in the mature peptide were arranged in the pattern of C-X16-C-X3-C-X9-C-X4-C-X1-C and stabilized the α-helix/β-sheet motif (CSαβ) with three disulfide bonds (C1-C4, C2-C5 and C3-C6) in the predicted tertiary structure. Moreover, by comparision with the similar three-dimensional structure of Anopheles gambiae defensin and phylogenetic analysis, it is suggested that HdDef1 might be a new member of the arthropod defensin family. Quantitative real-time PCR analysis reveals that HdDef1 transcripts were expressed constitutively in intestine, head, gill, hepatopancreas, mantle and foot, with the highest level in hepatopancreas. After being challenged with Vibrio harveyi, HdDef1 transcripts were induced significantly in hepatopancreas. The results indicate that HdDef1 might have an important function in host defense against invasive pathogenic bacteria, but its antimicrobial activity at protein level needs to be studied further.
Preparation and immunogenicity of Lactococcus lactis vaccine expressing Sip-Pgk fusion protein of Streptococcus agalactiae isolated from tilapia
Yumei YUAN, Cunbin SHI, Jiafa TAO, Defeng ZHANG, Chengwen SUN, Hua GONG, Zhibin HUANG, Yingtiao LAI
Latest Accepted  doi: 10.12131/20190092
[Abstract](185) [FullText HTML](150)
In order to develop a more effective Oreochromis sp. oral vaccine of Streptococcus agalactiae, we constructed a recombinant plasmid pNZ8148-sip-pgk which expresses Sip-Pgk fusion protein of S. agalactiae by using homologous recombination, and Lactococcus lactis NZ9000 pNZ8148-sip-pgk was obtained by electrotransformation of L. lactis NZ9000. The Sip-Pgk fusion protein was induced by nisin and tested by Western blot so that a Sip-Pgk fusion protein Lactobacillus oral vaccine was prepared. The tilapia was vaccinated orally by gavage with recombinant L. lactis NZ9000 pNZ8148-sip-pgk for twice or three times. ELISA was used to detect the level of serum antibody after immunization, and the relative immune protection rate was obtained by intraperitoneal injection of S. agalactis on the 18th day after immunization. The results show that the inducible protein size of the constructed recombinant Lactobacillus was 92 kDa, which was consistent with the size of the target protein. Compared with the second immunization, the third immunization with the fusion protein Lactobacillus vaccine could significantly improve the serum antibody level of tilapia and the immune protection against S. agalactiae. The serum level of Lactobacillus vaccine immunized with three times Sip-Pgk fusion protein was significantly higher than that of single protein group and PBS group, with the highest relative immune protection rate of 45.56%.
Comparison of quality and volatile components among five brands of cod sausages
Fan YE, Kang CHEN, Meijie TAO, Simin LI, Yalun CAO, Zhiyuan DAI
Latest Accepted  doi: 10.12131/20190120
[Abstract](204) [FullText HTML](109)
Five brands of cod sausages were evaluated for their gel properties, fatty acid composition and volatile components. Their gel strengths were 3 394.39 g·mm, 3 109.18 g·mm, 2 790.72 g·mm, 3 204.49 g·mm, 3 742.91 g·mm, respectively, while the whiteness was 69.61, 66.63, 63.88, 76.46 and 76.78, respectively. A total of 17, 15, 22, 19 and 15 fatty acids were detected. The contents of oleic acid, linoleic acid and palmitic acid were relatively high, while the relative contents of polyunsaturated fatty acids were 17.87%, 26.42%, 16.92%, 59.56% and 59.27%, respectively. The total amount of EPA and DHA in Brand B was the highest (18.00%). A total of 83 volatile components were identified, including six aldehydes, five ketones, six acid-phenols, 25 hydrocarbons, eight alcohols, 22 esters and 11 other components. Acid-phenols were the most in Brand A (61.12%) but only 7.66% in Brand B. The relative content of esters in Brand B was higher than those of the other components, reaching 50.68%. The volatiles were mainly composed of acid-phenols and esters in Brand C. In Brand D and Brand E, esters were the most, reaching 43.12% and 38.48%, respectively.
Correlation and path analysis of quantitative traits of clam (Callista erycina)
Haijun WEI, Zhenghua DENG, Mingqiang CHEN, Jijin WANG, Youning LI, Yu WANG
Latest Accepted  doi: 10.12131/20190126
[Abstract](211) [FullText HTML](114)
In order to study the relationship between morphological traits and body mass, 477 clams (Callista erycina) were randomly selected form Beihai, Guangxi Province to measure their shell length, shell height, shell width, anterior length, posterior length, stripe number and body mass by correlation analysis, path analysis and multiple stepwise regression analysis. The results show that there was extremely significant correlation among all the phenotypic traits (P<0.01), among which the correlation coefficient of shell length and anterior length was the highest (0.886), and that of posterior length and stripe number was the lowest (0.180). The correlation coefficient of body mass with shell width was the highest (0.865), and that of body mass with posterior length was the lowest (0.474). We established a regression equation of morphological traits for body mass (R2=0.812). The shell width influenced the body mass most with a path coefficient of 0.665, followed by the shell length (0.154) and shell height (0.117). The anterior length had the greatest indirect effect on the body mass (0.586), followed by shell height (0.580) and shell length (0.504). The shell width was the most important determinant of body mass.(0.442), followed by the shell length (0.024). The results suggest that breeding of C. erycina with body mass as breeding objective should mainly select shell width, and the synergistic breeding of anterior length and shell height should be strengthened at the same time.
Population genetic structure of Brushtooth lizardfish (Saurida undosquamis) based on mitochondrial cytochrome b gene sequences
Min LI, Zirong HUANG, Youwei XU, Zuozhi CHEN
Latest Accepted  doi: 10.12131/20190123
[Abstract](206) [FullText HTML](99)
We examined the population genetic structure of Brushtooth lizardfish (Saurida undosquamis) from the coastal waters and continental shelf of China based on the complete cytochrome b gene sequences. A total of 142 haplotypes have been derived from 266 individuals at eight sampling sites. Genetic diversity analysis shows that the S. undosquamis samples were characterized by rather high haplotype diversity (0.925 1~0.992 9) and relatively low nucleotide diversity (0.003 145~0.003 852). Median joining network shows that the haplotypes were connected in a star-like manner with four dominant haplotypes without clades of samples corresponding to sampling localities. Analyses of molecular variance suggest that nearly all the genetic variation (99.79%) was from individuals within population rather than from the populations. The pairwise FST reveals no genetic differentiation among different populations. A high rate of gene flow between populations implies a panmixia for S. undosquamis among the sampling sites. Neutrality tests show significant deviation of population historical dynamics from stable population model, and mismatch distribution analysis indicates a late Pleistocene expansion in S. undosquamis. The expansion time was estimated to be 40−100 thousands years ago. The results reveal that S. undosquamis from the coastal waters and continental shelf of China belong to the same population and can be managed as a unit in fisheries.
Economic and ecological benefits of annually two-cycle farming method of GIFT tilapia with in-pond raceway system
Qinglang YIN, Zhifang WANG, Zhongbao GUO, Pengfei BI, Yi ZHOU, Zhanyang TANG, Yongju LUO
Latest Accepted  doi: 10.12131/20190085
[Abstract](213) [FullText HTML](99)
To achieve an efficient utilization of pond aquaculture system and reduce the risk of cultivation, we investigated the annually two-cycle farming method of GIFT tilapia with in-pond raceway system. In the first breeding production, we kept the fish [(36.6±2.8) g] in two raceway for 122 d with the density of 183 ind·m−2 and 274 ind·m−2, respectively. In the second breeding production,we kept the fish [(185.2±15.8) g] in two raceway for 100 d with the density of 154 ind·m−2 and 215 ind·m−2, respectively. Meanwhile, Macrobrachium rosenbergii, Hypophthalmichthys molitrix and Aristichthys nobilis were cultured around the pond. Then we evaluated the water quality, aquaculture results and breeding benefits in the aquaculture process The results show that the survival rate of GIFT tilapia was 83.38%; the feed coefficient was 1.12; the aquaculture yield was 24 107 kg in the first breeding production. While in the second breeding production, the survival rate was 93.35%; the feed coefficient was 1.17; and the aquaculture yield was 25 730 kg. The yields of M. rosenbergii, Hypophthalmichthys molitrix and Aristichthys nobilis were 2 012 kg, 1 789 kg and 801 kg, respectively. For the breeding benefits, the average investment and income were 452 566 yuan per square hectare and 655 099 yuan per square hectare, respectively, with a profit of 202 533 yuan per square hectare and a return rate of investment of 44.75%. It is indicated that the annually two-cycle farming method with in-pond raceway system is effective for GIFT tilapia breeding, which can reduce the incidence of Streptococcus and improve the breeding efficient utilization.
Comparation of nutritional composition of Pyropia haitanensis from different sea areas of China
Shaoling YANG, Bo QI, Xianqing YANG, Wanling LIN, Jianchao DENG, Yanyan WU, Haixia MA, Hui RONG
Latest Accepted  doi: 10.12131/20190066
[Abstract](500) [FullText HTML](162)
We compared the nutritional composition of Pyropia haitanensis from six breeding sea areas in China. The results show that the moisture content of P. haitanensis was 9.68%−12.31%, and the moisture contents of sun-dried samples in Guangdong were significantly higher than those of the machine-dried samples in the other areas (P<0.05). The contents of crude fat were all lower than 0.5% (dry mass, same as below). The ash contents ranged from 7.85% to 9.55% (Xiapu highest, Dongshan lowest). The contents of protein were 33.40%−36.38% (Xiapu highest, Laiwu lowest). The contents of total amino acids and essential amino acids were 30.15%−32.41% and 11.52%−12.27%, respectively, both relatively high. However, the nutritional value score, chemical score and essential amino acid index of P. haitanensis from all the areas were all low. The essential amino acid index of Dongshan samples was the highest. Methionine+cysteine was the first limiting amino acid of P. haitanensis. Rich in essential minerals, the mineral elements contents of P. haitanensis varied greatly from area to area. The contents of K, Ca, Fe, Zn, Cu, Co and V in Xiapu samples, the contents of Na and Se in Nan'ao samples, the Mg content in Dongshan and Mn content in Wenzhou were the highest.
Calcium ion binding ability of tilapia skin hydrolysate and its antioxidant activity
Ruijie LI, Xiao HU, Laihao LI, Xianqing YANG, Shengjun CHEN, Yanyan WU, Wanling LIN, Hui RONG
Latest Accepted  doi: 10.12131/20190102
[Abstract](424) [FullText HTML](157)
By digesting tilapia (Oreochromis mossambicus) skin with neutral protease, Protamex1.5L and alkaline protease, we studied the binding ability of different enzymatic products to calcium ions (Ca2+), compared the antioxidant capacity of enzymatic hydrolysates and their combinations, and analyzed the Fourier infrared spectrum of the conjugate. The results show that the enzymatic hydrolysate of Protamex1.5L hydrolyzed tilapia skin had the highest calcium ion binding rate of 87.79%. All the three tilapia skin hydrolysates had antibacterial properties, and the DPPH free radical scavenging rate, OH radical scavenging rate and reducing power of the products of Protamex1.5L enzymatically tilapia skin were 51.46%, 17.26% and 0.09, respectively. After the tilapia skin hydrolysate (TSH) was combined with calcium ions, the DPPH free radical scavenging rate and hydroxyl radical scavenging rate of calcium ion chelate (TSH-Ca) decreased, but the reducing power was enhanced. Fourier transform infrared spectroscopy confirms that TSH had combined with calcium ion and calcium ion had combined with amino nitrogen atom and carbonyl oxygen atom in TSH.
Effect of dietary protein level on digestive enzyme activity and histological structure in intestine and liver of juvenile Schizopygopsis younghusbandi Regan
Jian WANG, Benhe ZENG, Zhaoli XU, Bianbian ZHANG, Haiping LIU, Wanliang WANG, Jinlin WANG, Jianshe ZHOU, Liping HUANG
Latest Accepted  doi: 10.12131/20190107
[Abstract](392) [FullText HTML](150)
To explore the effects of different feed protein levels on the digestive enzyme activity and histological structure in the intestine and liver of juvenile Schizopygopsis younghusbandi Regan, we designed six kinds of equal-energy experimental feeds with different protein levels (20%, 25%, 30%, 35%, 40%, 45%) to feed the juveniles with initial body mass of (22.42±0.56) g for 60 d. The results show that with the increase of feed protein level, the protease activity in intestine and liver increased first then declined. The protease activity in 35% protein group was significantly higher than that in the other groups (P<0.05). The lipase and amylase activities reduced significantly (P<0.05). The wall thickness and villus height of foregut, midgut and hindgut all increased and then decreased (P<0.05). The wall thickness of foregut and midgut were the highest in 30% group, while the wall thickness of the hindgut was the highest in the 35% group. The villus height of foregut, midgut and hindgut in 30% group were the highest. Feed protein level higher than 35% may damage liver tissue structure. Under this condition, considering the digestive enzymes activity and histological structure of intestines and liver, the optimum protein level of juvenile S. younghusbandi Regan should be 30%.