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A preliminary study on autumn feeding habits of bigeye tuna (Thunnus obesus) in subtropical waters of North Pacific
Yingchao DANG, Yilin CHEN, Xiaojie DAI, Yunkai LI, Feng WU, Pan LIU
Sixth Proofread  doi: 10.12131/20190184
[Abstract](790) [FullText HTML](567) [PDF 1254KB](23)
We analyzed the stomach contents of 146 bigeye tuna (Thunnus obesus) collected in the subtropical waters of the North Pacific (150°W−164°W, 30°N−37°N) from September to December in 2018 by the Chinese Longline Fisheries Observer Programme. A total of 36 bait species belonging to 28 families were identified. Alepisaurus ferox, Eucleoteuthis luminosa, Lestidium prolixum and Diaphus sp. were the dominant baits, whose relative importance index ratios (IRI%) were 25.65%, 14.48%, 7.56% and 6.77%, respectively. The feeding intensity of bigeye tuna reached the maximum value in the range of 100−110 cm fork length and at Stage III of gonadal maturity, while reached the minimum value at Stage V. Moreover, higher feeding intensity was observed at water layer of 150−250 m. The results improve the understanding of the biological characteristics and feeding habits of bigeye tuna, in addition to its important role in the ecosystem and food network structure.
Degradation of Porphyra haitanensis polysaccharide by ultrasonic assisted hydrogen peroxide method and its antioxidant activity analysis
Haichao HUANG, Jinxu WANG, Chuang PAN, Xianqing YANG, Bo QI, Laihao LI, Yongqiang ZHAO
Sixth Proofread  doi: 10.12131/20190220
[Abstract](826) [FullText HTML](549) [PDF 1195KB](7)
We have compared the degradation effects of ultrasonic method, hydrogen peroxide method and ultrasound-assisted hydrogen peroxide method on Porphyra haitanensis polysaccharide, and finally optimized ultrasonic assisted hydrogen peroxide degradation of polysaccharides by single factor and orthogonal test, using DPPH scavenging rate as the index. Meanwhile, we compared the antioxidant activity of polysaccharides and analyzed its correlation with molecular mass, structural characteristics and physicochemical properties. The results show that the IC50 (Half maximal inhibitory concentration) of DPPH scavenging reduced from 9.37 mg·mL−1 to 1.71 mg·mL−1 under the conditions of 10% hydrogen peroxide, 65 ℃ and 2.5 h. Gel permeation chromatography shows that the molecular mass of polysaccharide decreased from more than 670 kD to 235 835 D before and after degradation. FT-IR shows that the absorption peaks of the polysaccharide did not change. The monosaccharide composition was almost the same with PMP column derivatization according to HPLC analysis, while the content of uronic acid decreased. Moreover, the Sulfate-group content increased but the 3,6-endogalactose content decreased obviously. Therefore, the ultrasonic assisted hydrogen peroxide method can degrade P. haitanensis polysaccharides and improve the antioxidant activity. The results provide references for the preparation of low molecular mass polysaccharides and analysis of structure-activity relationship.
Study on taxonomic diversity of fish in Zhubi Reef of Nansha Islands
Yuanjie LI, Jun ZHANG, Zuozhi CHEN, Yan'e JIANG, Yuyan GONG, Yancong CAI, Yutao YANG
Sixth Proofread  doi: 10.12131/20190159
[Abstract](822) [FullText HTML](558) [PDF 768KB](9)
According to the survey data of gill net and hand fishing in Zhubi Reef of Nansha Islands in 1999−2018, we analyzed Zhubi Reef fish species composition and the classification of diversity, calculated the average classification difference index (Δ+) and classification difference variation index (Λ+). Altogether 152 species of reef fish belonging to 11 Orders, 43 Families and 93 Genera had been found. Among them, Perciformes fish accounted for an absolute advantage (76%). The Δ+ and Λ+of Zhubi Reef fish were 58.75 and 102.60, respectively. Compared with the composition of fish communities in different ecosystems at home and abroad, the Δ+of the fish in Zhubi Reef was higher than those in Zhaoshu Island, Milne Bay and San Jose Island, but lower than those in the East China Sea Shelf, the South China Shelf of Nansha Islands, Beibu Gulf and Daya Bay. The Λ+ of the fish in Zhubi Reef was lower than those in the other islands. It is indicated that the genetic relationship among the species in Zhuubi Reef fish community is closer than those in the East China Sea Shelf, the southwest shelf of Nansha Islands, Beibu Gulf and Daya Bay, but farther than those in Zhaoshu Island, Milne Bay and San Jose Island. The fish diversity of Zhubi Reef is characterized by higher species diversity but lower taxonomic diversity. However, the reef is vulnerable to human activities and should be protected in a timely manner.
Correlation among growth performance, morphological traits and body mass of Eleutherollema tetradactyuulum cultured in indoor circulating aquaculture system and aquaculture pond
Junwei LI, Youjun OU, Jiufu WEN, Ruiping HU, Changbo ZHU, Junnan LAN, Jia'er LI, Hui ZHOU
Sixth Proofread  doi: 10.12131/20190155
[Abstract](1180) [FullText HTML](874) [PDF 640KB](5)
We applied correlation analysis and path analysis to explore the relationship between the body mass and the 12 morphological traits of Elentheronema tetradactylum cultured in indoor circulating aquaculture system and aquaculture pond, which had significant correlation (P<0.05), and the correlation among the morphological traits of E. tetradactylum in the two systems was very significant (P<0.01). The descending order of morphological traits which affected on the body mass of E. tetradactylum in indoor circulating aquaculture system and aquaculture pond were fork length>body length>head length>caudal peduncle height>total length, and total length>caudal peduncle height>fork length>body length>body height, respectively. The path analysis reveals that body length, body height, head length, body width and eye diameter had significant direct effects on the body mass of E. tetradactylum in indoor circulating aquaculture system (P<0.05). The total length, caudal peduncle height, body height, trunk length and head length had significant direct effects on the body mass of E. tetradactylum in aquaculture pond system (P<0.05). Besides, the total decision coefficients of those morphological traits to the body mass were 1.418 and 0.968 in indoor aquaculture system and aquaculture pond, respectively. The results reveal that larger variation coefficient of fish in aquaculture pond is conducive to the breeding of improved species, while more uniform specification of indoor circulating water culture is conducive to production. In different aquaculture environment, the correlation analysis of morphological traits and body mass of E. tetradactylum can provide theoretical basis for its large-scale cultivation and breeding technology optimization.
Relationship between catch rate of longline albacore (Thunnus alalunga) and environmental factors in South Pacific
Jiarong ZHANG, Xiaoming YANG, Xiaojie DAI, Lijin ZOU
Sixth Proofread  doi: 10.12131/20190178
[Abstract](786) [FullText HTML](575) [PDF 1542KB](8)
Based on the data of albacore logbook (Thunnus alalunga) collected by mainland China from 2015–2017 in the South Pacific and the marine environmental data in the same period, we analyzed the relationship between catch rate and environmental factors, so as to examine the effects of environmental factors at different depths on T. alalunga by establishing a GAM (Generalized additive model). In addition, we had obtained the correlation coefficient of each environmental factor (those with large correlation were grouped and modeled) by correlation analysis. The results show that: 1) Sea surface temperature and sea temperature at depth of 120 m, sea surface temperature and sea surface height, sea temperature at depth of 120 m and sea surface height, sea temperature and sea salinity at depth of 300 m were highly correlated factors. However, sea surface salinity, chlorophyll a concentration and northward sea surface wind had no significant correlation with the other environmental factors. 2) The explained cumulative deviance was 30%–40%; the environmental factors sorted by importance are as follows: sea temperature at depth of 120 m, sea surface temperature, sea temperature at depth of 300 m, sea salinity at depth of 120 m, sea surface height, sea salinity at depth of 300 m, sea surface salinity, mixed layer depth, northward sea surface wind, eastward sea surface wind and chlorophyll a concentration. 3) The sea temperature at depth of 120 m was negatively correlated with CPUE (Catch per unit effort) at 15–30 ℃. The trend of sea surface temperature was similar to the sea temperature at depth of 120 m, with a positive correlation at 25–28 ℃. The sea temperature at depth of 300 m and CPUE showed a significant positive relationship at 10–18 ℃.
Comprehensive rating quantitative assessment on aquaculture environment of subtropical bay in northern South Sea China
Xiuli LIAO, Honghui HUANG, Zhanhui QI, Ming DAI, Huaxue LIU
Sixth Proofread  doi: 10.12131/20190067
[Abstract](1191) [FullText HTML](850) [PDF 1228KB](6)
According to the ecological environment survey data of three subtropical aquaculture bays (Maowei Sea, Dapeng Cove and Baisha Bay) along the northern coast of the South China Sea from 2011 to 2012, and by appling methods of comprehensive grading evaluation of aquaculture area as well as river comprehensive water quality index (Iwq) evaluation, we compared the advantages and disadvantages of ecological environment of the same level quantitatively based on classification of marine environment. The results show that only two of the 12 voyages in the three bays (autumn and winter in Dapeng Cove) had a good environmental rating, and the other 10 were medium. In spring, the rating of the three bays was medium and with simila index. In summer, autumn and winter, the environmental quality of Baisha Bay was the worst. In the past two years, five water environmental factors had been alarmed, and the three bays were at risk of eutrophication. The influence of seasonal change on the bay environment increased with the increase of latitude. It is found that the improved Iwq index is more efficient in comparing the environmental conditions of the same level, but its comparability among different levels is uncertain.
Spatial distribution characteristics analysis and resources assessment of fish in Lugu Lake
Shuo HUANG, Lianxiang LI, Wei DAO, Xu LI
Sixth Proofread  doi: 10.12131/20190180
[Abstract](737) [FullText HTML](545) [PDF 5391KB](14)
From August 15 to 19, 2018, we assessed the spatial distribution and resources of fish in Lugu Lake, Yunnan Province for the first time by using lowrange elite-7 Ti echo detector. Zigzag route was used to detect the whole Lugu Lake, with a total voyage of 42.71 km. Based on the depth variation value, the lake was divided into a number of detection units for fish resources evaluation, and the spatial distribution map was drawn based on the density of each unit by inverse distance weighting (IDW). The results of hydroacoustic survey shows that the spatial distribution of fish in Lugu Lake was uneven. In the horizontal direction, most fish clusters were distributed in the coastal annular waters, among which the fish density in the waters near Xiaoyuba was the highest, while the fish density in the middle of the lake was the lowest; in the vertical direction, the fish distribution in the surface waters was relatively concentrated. In August 2018, the fish density in Lugu Lake was 0.153·(1 000 m3)−1; the total number of fish was 243 900 and the total resource was 50.55 t (Carassius auratus: 211 700 ind., total mass of 17.36 t; Cyprinus carpio: 17 400 ind., total mass of 23.01 t; Ctenopharyngodon idellus: 86 300 ind., total mass of 8.63 t; Paramisgurnus dabryanus: 6 800 ind., total mass of 1.33 t; Schizothorax microstomus: 700 ind., total mass of 0.22 t). In this survey, there was no records of S. ninglangensis and S. labrosus which had been found in previous investigation.
Detection of antibiotics resistance and distribution of resistance genes in Vibrio parahaemolyticus from cultured shrimp
Wenjuan WEI, Shu ZHAO, Yuan WANG, Junfang ZHOU, Xincang LI, Wenhong FANG
Sixth Proofread  doi: 10.12131/20190165
[Abstract](775) [FullText HTML](562) [PDF 670KB](4)
We used agar dilution method to detect the resistance of 36 strains of Vibrio parahaemolyticus to 16 drugs. And used PCR amplication and DNA sequencing to detect the antimicrobial resistance to quinolones (qnrA, qnrB, qnrS, qnrVC), phenicols (cat, optrA, floR, cfr), tetracyclines (tetA, tetB, tetM), sulfonamides (sul1, sul2, sul3), aminoglycosides (strA, strB, aadA, aacA), rifampicin (arr), β-lactams (carB) and macrolides (erm). The results indicate that the isolates exhibited high resistance to ampicillin (88.9%) and sulfamethoxazole (SMZ, 66.7%), all susceptible to neomycin sulfate, gentamicin, ceftriaxone and meropenem. In general, multi-drug resistance (MDR) was highly prevalent (61.1%), and one isolate was resistant to six antimicrobials. Furthermore, 72.2% and 58.3% of the isolates were primarily mediated by qnrVC and strB, respectively; and the macrolides and rifamycin resistant genes were not detected in all the isolates. Obvious mismatch was found between the antimicrobial resistance phenotypes and genotypes, revealing the complexity of resistance to V. parahaemolyticus.
Anatomy and histological observation of digestive system in Schizothorax eurystomus
Jie WEI, Xiquan CAO, Yongli REN, Rehemana AIKEBAIER, Zhulan NIE
Sixth Proofread  doi: 10.12131/20180262
[Abstract](1369) [FullText HTML](940) [PDF 950KB](6)
Anatomy, paraffin section and HE staining were used to observe the anatomical characteristics and tissue slice in the digestive tract of Schizothorax eurystomus. The results show that the wall of digestive tract included mucosa, submucosa, muscularis and serosa from inner to outer. The main difference lay in mucosa and muscular layers. The mucosa layer of esophagus was covered with stratified epithelium and abundant goblet cells. The mucosae in the foregut and midgut were obviously lined by a simple columnar epithelium with abundant goblet cells, brush border and lymphocytes. The mucosa of hindgut was composed with pseudostratified columnar epithelium, goblet cells and lymphocytes. From front to back, the number of goblet cells of intestine increased gradually. The muscularis of esophagus and foregut consisted of internal-circular muscle layer and external-longitudinal muscle layer. However, the skeletal muscle and smooth muscle were distributed in muscularis of esophagus and foregut. The muscularis of midgut and hindgut consisted of internal-spiral and external-longitudinal smooth muscle layers. The digestive gland was composed of liver and pancreas, and the pancreas was diffuse in the liver. The hepatic lobule was unconspicuous. In conclusion, the histological structure of digestive system of S. eurystomus is related with its function and feeding habit.
Fish community structure and environmental effects of West River
Yingqiu ZHANG, Daotian HUANG, Xinhui LI, Qianfu LIU, Jie LI, Yuefei LI, Jiping YANG, Shuli ZHU
Sixth Proofread  doi: 10.12131/20190142
[Abstract](1429) [FullText HTML](993) [PDF 1454KB](5)
From 2016 to 2018, we seasonally collected fish and monitored the environmental factors at the six sites from Guiping to Zhaoqing in the West River, the main stream of the Pearl River. In total, we collected 99 species belonging to 12 Orders and 29 Families. The species number collected for each sampling ranged from 10 to 45, while the Shannon-Weiner index ranged from 0.90 to 2.93, and the evenness index ranged from 0.30 to 0.89. The species variation was agreed with patterns of seasonal turnover and spatial turnover. As revealed by the index of relative importance, Cirrhinus molitorella, Megalobrama terminalis and Squaliobarbus curriculus were the most dominant fish species. The permutational multivariate analysis of variance indicates that the fish community structure varied significantly among seasons and sites. The significant difference between summer and winter was mainly caused by the weight percentage variation (W%) of Cyprinus carpio, C. molitorella, M. terminalis and S. curriculus. The significant difference between Guiping and lower reaches of Wuzhou and Zhaoqing was mainly caused by the number percentage (N%) variation of C. molitorella, M. terminalis and Squalidus argentatus, and W% variation of C. molitorella, M. terminalis, C. carpio, Hypophthalmichthys molitrix and Oreochromis niloticus. Redundancy analysis explains 49.92% variation of fish N% and 49.61% of fish W%; the most important influencing variables are distance to estuary, water temperature, water transparency and runoff; C. molitorella distributes in water of low transparency and high temperature; M. terminalis and H. molitrix distributes in lower reach; S. curriculus distributes in middle and upper reach; C. carpio distributes in water of high transparency and low temperature.
Comparison of development and growth of hybrid Chromileptes altivelis () × Epinephelus tukula ()
Zhentong LI, Yongsheng TIAN, Meiling CHENG, Yuping WU, Jingjing ZHANG, Ziqi LI, Linna WANG, Wenhui MA, Zunfang PANG, Lijuan SUN, Jieming ZHAI
Sixth Proofread  doi: 10.12131/20190168
[Abstract](1181) [FullText HTML](854) [PDF 1857KB](3)
We performed breeding experiments with Chromileptes altivelis as the female parent and Epinephelus tukula as the male parent by artificial fertilization to breed new species of groupers with excellent traits. Besides, we observed and compared the embryonic development and growth characteristics of C. altivelis (♀) ×E. tukula (♂) and C. altivelis by microscope (Nikon E200) and anatomic microscope (Olympus). The results show that the fertilized eggs of the hybrid and C. altivelis took 24 h 50 min and 25 h 8 min to accomplish the embryo development under the conditions of water temperature 27 ℃, salinity 30, pH 8.1 with the micro-flowing water and micro-inflated water, respectively. The post-embryonic development of the hybrid had experienced four stages of early larva (0−3 d), late larva (4−40 d), juvenile (41−60 d) and young fish stages (after 61 d). At 330 days of age, the total lengths of the hybrid and C. altivelis were (23.57±0.94) cm and (18.35±0.72) cm, respectively; and the body masses were (220.5±25.3) g and (142.6±0.58) g, respectively. The total length and body mass of the hybrid were 1.28 and 1.55 times that of the C. altivelis, respectively. Compared with C. altivelis in the external morphological traits, the hybrid was slender and the head was larger, the black spots on the body surface was distributed disorderly, and the fins of each part was relatively small. Based on our tracking observation on embryo and larval development of hybrid, it is confirmed that the distant hybridization combination of C. altivelis (♀) ×E. tukula (♂) is feasible, and the hybrid shows the merit of heterosis, which provides scientific basis for distant hybridization and the cultivation of new varieties of groupers.
Development and identification of SSR markers based on RNA-seq data of Diodon hystrix
Jun MA, Jiaxin LIU, Zhijing JIANG, Yongsen ZHOU, Zhenhao YU, Haishan WANG, Yan CHEN, Pan CHEN, Hai HUANG
Sixth Proofread  doi: 10.12131/20190147
[Abstract](1282) [FullText HTML](906) [PDF 1714KB](7)
The transcriptome sequences of Diodon hystrix were obtained by RNA-seq technology, and a total of 221 762 Unigenes were generated by de novo assembly with N50 of 2 240 nt and GC content of 46.20%. By using MISA software, 106 221 SSR loci, which distributed in 62 451 Unigenes with a frequency of 28.16%, were detected from the RNA-seq data of D. hystrix. The dominant repeat units were mononucleotide, dinucleotide and trinucleotide, which accounted for 48.99%, 32.57% and 14.72% of the total SSR loci, respectively. The A/T was the main repeat unit in mononucleotide, accounting for 46.21% of the total SSR loci, while the AC/GT and AGG/CCT were the dominant repeat units in di- and thinucleotides, accounting for 21.90% and 2.70% of the total SSR loci, respectively. Altogether 17 563 pairs of primers were designed by selecting SSR loci with length greater than 20 bp. Then 160 pairs of primers were randomly selected for amplification and identification, and 95 pairs of effective amplification primers were screened, accounting for 59.38%. Thirty pairs of stable and repeatable polymorphic primers were obtained from the effective amplification primers by polymorphism verification (31.58% of the effective amplification primers). Among them, 15 pairs of primers showed high polymorphism (PIC>0.5), which were benefit for assessing the diversity of D. hystrix population. These results indicate that the transcriptome data of D. hystrix can be used as an effective source for the development of stable SSR markers, and the obtained polymorphic SSR loci can provide foundation for the further study of genetic map and genetic diversity of D. hystrix.
Effects of nitrogen, phosphorus and carbon on growth of seven marine microalgae
Zuoyi LIU, Shibin QI, Ning HE, Jiefeng KOU, Kaifeng SUN
Sixth Proofread  doi: 10.12131/20190089
[Abstract](1373) [FullText HTML](990) [PDF 1384KB](3)
In order to screen fine algae species (strains) for in situ treatment of aquaculture tail water, we investigated the effects of nitrogen (nitrate, ammonium and urea), phosphorus (phosphate) and carbon (carbonate) on the growth of seven marine microalgae (Cochlodinium geminatum, Karenia mikimotoi, Skeletonema costatum, Chaetoceros muelleri, Phaeocystis globosa, Platymonas subcordiformis, Nannochloropsis oculata) in batch cultures. The results reaveal that the growth rates of microalgae were positively correlated with nutrients concentration. Compared with the control, the enhancements on the specific growth rate were 35%, 19% and 19% in C. geminatum, S. costatum and N. oculata under carbonate treatments. The enchancements on the specific growth rate under phosphate, nitrate, ammonium and urea were 25.01%−446.60%, 16.54%−77.52%, 15.79%−88.82% and 25.16%−71.43%, respectively. In general, the maximal specific growth rates (highest in P. globosa) of seven marine algae under carbon, nitrogen and phosphorus were negatively correlated with cell size, while those of P. subcordiformis and N. oculata were not significantly different with red tide microalgae except P. globosa. The nitrate and phosphate uptake rates were positively correlated with cell size, but the utilization efficiency of nitrogen/phosphorus per cell was negatively correlated with cell size. The N/P ratios in all culture medium increased. The phosphorus uptake rates were higher than nitrogen uptake rates. P. subcordiformis and N. oculata can be used in algal absorption of nitrogen and phosphorus in aquaculture tail water.
Primary study on differentially expressed genes screening of Monopterus albus and their regulation mechanism
Huanhuan HUO, Yu LIU, Qiubai ZHOU, Feng GUO, Lili WEI, Mo PENG, Yanping ZHANG, Wenjing CHEN
Sixth Proofread  doi: 10.12131/20190176
[Abstract](774) [FullText HTML](576) [PDF 981KB](4)
In order to reveal the regulatory mechanism of growth related genes in eels (Monopterus albus), we carried out a transcriptome sequencing analysis on the liver of the eels that had significant growth difference with the same parent. A total of 19 149 genes were obtained by transcriptome sequencing, among which 598 were differentially expressed (303 and 295 were significantly up-regulated and down-regulated, respectively). KEGG pathway analysis shows that 598 differentially expressed genes belonged to 262 pathways, among which 38 pathways are significantly enriched. The GO functional annotation reveals that the seven differentially related genes were col1α1, nkx6.1, nnos, plexina4, igfbp1, pcgf1and h3.3, and variation in the expression levels of these genes had regulated the development and physiological activities of the nervous system, endocrine system and digestive system of the eels, which then affected their growth. Combined with KEGG pathway analysis, it is found that the leishmaniasis pathway, in which col1α1 is located, and the arginine and proline metabolic pathway, in which nnos is located, are significantly enriched, revealing their important influence on the growth of eels.
Beak microstructure and its application in age and growth study of Dosidicus gigas in open sea of Chile
Bilin LIU, Na LIU, Jianhua LI, Xinhao ZHANG
Sixth Proofread  doi: 10.12131/20190116
[Abstract](1374) [FullText HTML](1014) [PDF 984KB](4)
In this study, the age and growth of Dosidicus gigas were investigated by analyzing the microstructure of upper beak rostrum sagittal section (RSS), based on 148 specimens collected from the open sea of Chile. The results show that its RSS was composed of hood and crest, where periodic growth bands including one light and one dark increment were distinct. The increments of hood and crest met together at the region of internal rostral axis, showing a pattern of ‘<’. The stress marks and aberrant structures might relate to special ontogenetic events or external accident. The back−calculated hatching date was deduced from March to November, mainly from June to July in 2009. The relationship between mantle length (ML) and age can be described as power function. The average IGR (Instantaneous growth rate) and AGR (Absolute daily growth rate) of ML of female D. gigas were 0.14 %˙d−1 and 0.60 mm˙d−1, respectively, and the average IGR and AGR of ML of males were 0.11 %˙d−1 and 0.47 mm˙d−1, respectively. The results can provide not only a new method for age and growth study of Ommastrephidae but also important references for Chinese scientists to perform relevant researches.
Display Method:
Research Paper
2019, 15(6).  
[Abstract](1020) [PDF 2165KB](15)
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
2019, 15(6): 1-8.   doi: 10.12131/20190045
[Abstract](2383) [FullText HTML](1191) [PDF 1040KB](22)
Defensin is one of the most important antimicrobial peptides (AMPs) that participate in invertebrate innate immunity against invading pathogens. In the present study, a novel defensin was identified in small abalone (Haliotis diversicolor) that was denoted as HdDef1 by using RNA-seq and RACE techniques. The HdDef1 cDNA contained a 201 bp open reading frame (ORF) encoding 66 amino acids including 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 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 further study.
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
2019, 15(6): 9-18.   doi: 10.12131/20190092
[Abstract](2186) [FullText HTML](1300) [PDF 1569KB](14)
In order to develop a more effective Oreochromis sp. oral vaccine of Streptococcus agalactiae, we constructed a recombinant plasmid pNZ8148-sip-pgk which expressed 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 kD, 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%.
Relationship of hepatopancreas colours with lipid and mineral contents in cultured grass carp during winter
Chunhong HUANG, Jiali LI, Yanju LEI, Zhongguo XIE
2019, 15(6): 19-24.   doi: 10.12131/20190073
[Abstract](2508) [FullText HTML](1279) [PDF 619KB](22)
To clarify the relationship between hepatopancreas colours and 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 contents in spot, white and yellow hepatopancreas all increased significantly (P<0.05). Cu and As contents in spot hepatopancreas, and Mg, Fe, Cu contents 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 contents 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).
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
2019, 15(6): 25-33.   doi: 10.12131/20190085
[Abstract](2249) [FullText HTML](1123) [PDF 655KB](9)
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 (Oreochromis niloticus) 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 densities 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 densities 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, H. molitrix and A. 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.
Correlation and path analysis of quantitative traits of clam (Callista erycina)
Haijun WEI, Zhenghua DENG, Mingqiang CHEN, Jijin WANG, Youning LI, Yu WANG
2019, 15(6): 34-40.   doi: 10.12131/20190126
[Abstract](2207) [FullText HTML](1186) [PDF 752KB](26)
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, number of growth lines 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 between shell length and anterior length was the highest (0.886), and that between posterior length and number of growth lines was the lowest (0.180). The correlation coefficients of body mass with shell width and posterior length were the highest (0.865) and the lowest (0.474) , respectively. 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 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 shell 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
2019, 15(6): 41-48.   doi: 10.12131/20190123
[Abstract](2286) [FullText HTML](1168) [PDF 797KB](19)
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.
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
2019, 15(6): 49-55.   doi: 10.12131/20180220
[Abstract](2318) [FullText HTML](1261) [PDF 955KB](28)
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.
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
2019, 15(6): 56-64.   doi: 10.12131/20190024
[Abstract](2920) [FullText HTML](1327) [PDF 996KB](25)
To explore the carrying capacity of fishery resources in the coastal waters of Dapeng Peninsula, Shenzhen, considering 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.
Comparative study on credibility of fishing information of electronic fishing logs of trawlers and fishing information acquired by Beidou position data
Fei FENG, Yanbo ZHOU, Sen CHEN, Enge XIE, Qia'er WU
2019, 15(6): 65-74.   doi: 10.12131/20190110
[Abstract](1988) [FullText HTML](1103) [PDF 2183KB](25)
To analyze the accuracy and credibility of electronic fishing log data, we extracted and analyzed the fishing time, fishing hauls and fishing area of five trawlers ('Yuexinhui fishing 01282', 'Yuexinhui fishing 01240', 'Yuexinhui fishing 01286', 'Yuexinhui fishing 01239', 'Yuemaobin fishing 47239', 'Yuexinhui fishing 02163', 'Yuemaobin fishing 42278', 'Yuexinhui fishing 00070' and 'Yuexinhui fishing 01268') from August 17, 2018 to April 30, 2019 by Beidou position data, and then compared them with relevant information of electronic fishing logs data. The repetition rates of five trawlers extracted from the electronic fishing logs data and Beidou position data were 36.7%, 64.8%, 71.4%, 81.5%, 24.7%, 46.7%, 66.7%, 79.6% and 68.9%, respectively. The repetition rates of fishing areas were 80%, 86.9%, 65.7%, 74.7%, 75.3%, 85.6%, 71.6%, 56.9% and 65.2%, respectively. The repetition rate of fishing hauls were 65%, 86.4%, 60%, 70%, 75.3%, 67.1%, 54.4%, 62.1% and 35.4%, respectively. The correlation analysis between fishing time and catches shows that the fishing time of 'Yuexinhui fishing 01282', 'Yuexinhui fishing 01240', 'Yuexinhui fishing 01239' and 'Yuemaobin fishing 47239' correlated with catches very significantly (P<0.01); the fishing time of 'Yuemaobin fishing 42278' correlated with catches significantly (P<0.05); the fishing time of 'Yuexinhui fishing 01282', 'Yuexinhui fishing 01286', 'Yuexinhui fishing 00070' and 'Yuexinhui fishing 01268' had no significant correlation with catches (P>0.05), which reflects that the accuracy and feasibility of electronic fishing logs data still need to be improved.
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
2019, 15(6): 75-80.   doi: 10.12131/20190066
[Abstract](2671) [FullText HTML](1331) [PDF 578KB](27)
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. The mineral elements contents were rich in P. haitanensis and 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.
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
2019, 15(6): 81-87.   doi: 10.12131/20190003
[Abstract](2578) [FullText HTML](1294) [PDF 672KB](14)
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 value) 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 value. The precooling extended the shelf life of M. salmoides fillets up to 3 d during ice storage comparing with the control group.
Optimization of multi-enzymatic extraction of polysaccharide from Gelidium amansii by response surface methodology
Ruonan PEI, Honglei ZHAI, Bo QI, Xianqing YANG
2019, 15(6): 88-95.   doi: 10.12131/20190081
[Abstract](2654) [FullText HTML](1339) [PDF 1680KB](15)
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.
Comparison of quality and volatile components among five brands of cod sausages
Fan YE, Kang CHEN, Meijie TAO, Simin LI, Yalun CAO, Zhiyuan DAI
2019, 15(6): 96-105.   doi: 10.12131/20190120
[Abstract](2210) [FullText HTML](1170) [PDF 713KB](17)
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.
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
2019, 15(6): 106-111.   doi: 10.12131/20190102
[Abstract](2612) [FullText HTML](1253) [PDF 943KB](17)
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 skins 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 reveals that 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
Jian WANG, Benhe ZENG, Zhaoli XU, Bianbian ZHANG, Haiping LIU, Wanliang WANG, Jinlin WANG, Jianshe ZHOU, Liping HUANG
2019, 15(6): 112-119.   doi: 10.12131/20190107
[Abstract](2448) [FullText HTML](1291) [PDF 867KB](13)
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, 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 highest in 30% group, while the wall thickness of the hindgut was highest in the 35% group. The villus height of foregut, midgut and hindgut were highest in 30% group. 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 should be 30%.
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Construction of knock-out mutant of vhh in Vibrio harveyi and its related biological characteristics analysis
Yaqiu ZHANG, Yiqin DENG, Juan FENG, Can MAO, Jianmei HU, Youlu SU
Latest Accepted  doi: 10.12131/20190211
Vibrio harveyi is an important pathogen of aquatic animals. In order to study the biological characteristics of the strain after the absence of hemolysin gene vhh, the knock-out mutant of vhh in V. harveyi was constructed by homologous recombination technique. Moreover, the biological characteristics of the wild type strain and the mutant strain were compared. The results show that the deletion of vhh gene did not affect the growth of the strain, neither the secretion of extracellular protease, the stress response to H2O2 and Cu2+, the uptake and utilization of iron, and the 15 antibiotics resistance and biofilm formation, but it caused the strain to swim and surge significantly. In addition, although vhh was highly expressed in the wild type strain, the strain did not show hemolytic activity. The results indicate that vhh negatively regulates the bacterial motility. The study provides novel information for understanding the function of vhh gene in V. harveyi.
Aquaculture of Strongylocentrotus intermedius in Fujian coastal areas
Yaqing CHANG, Chong ZHAO, Fangyuan HU, Jian SONG, Xiaofei LENG, Xiujin LIAO, Jia LUO, Mingtai LIU, Weijie ZHANG
Latest Accepted  doi: 10.12131/20190156
In order to explore the feasibility of Strongylocentrotus intermedius of seasonal breeding in Fujian coastal areas, we moved a new breed of S. intermedius “Dajin” southward to Fuzhou sea area in November 2018. The tested S. intermedius was divided into two types: large-size (3 cm test diameter) and small-size (1 cm test diameter). Using the existing abalone breeding facilities, we regularly fed Laminaria japonica and Gracilaria lemaneiformis. After six months of breeding, the test diameter of large-size S. intermedius bred in Fuzhou had reached (55.90±2.63) mm, while the body mass had reached (56.30±6.92) g and the gonadal index reached (15.02±1.5) %. The gonadal development entered the stage of premature (Stage III) with good quality, which was significantly greater than the test diameter (40.97±4.01) mm and body mass (18.60±4.27) g for S. intermedius bred in Dalian in the same period (P<0.05). Besides, the test diameter of small-size S. intermedius in Fuzhou had reached (40.97±0.97) mm, while the body mass had reached (23.18±0.37) g and the gonadal index had reached (9.64±1.00)%. Thus, it is suggested that seasonally breeding S. intermedius in the coastal areas of Fujian province in winter and spring is feasible. Feeding with local fresh algae on basis of existing facilities and abalone cages leads to higer growth rate of S. intermedius than those bred in Dalian in the same period. The important way to meet the increasing market demand of S. intermedius is to move the breeding southward along Fujian coast.
Comparison on morphology and body spots characteristics between backcross progenies and their parents of Siniperca chuatsi
Lei WEI, Shuqin ZHU, Wei LIU, Jinliang ZHAO, Yezhou QIAN, Chao WU, De QIAN
Latest Accepted  doi: 10.12131/20190219
Since morphology and body spots characteristics are important breeding traits in mandarin fish (Siniperca chuatsi) crossbreeding, we analyzed the difference of quantifiable morphological traits for the backcross progeny [S. scherzeri ♀× (S. scherzeri ♀×S. chuatsi ♂)] and parental offspring (S. scherzeri, S. scherzeri ♀×S. chuatsi ♂) by multiple comparison, hybrid index, principal component analysis and discriminant analysis, and observed the body spots of the backcross. The results show that the average hybrid index of the backcross was 38.73. The morphometric difference analysis and hybrid index indicate that the backcross progeny were biased toward S. scherzeri. Principal component analysis and discriminant analysis reveal that the main differences lay in head angle, body height/body length, head height/head length, and C (the length from the back of the angle bone to the beginning of the ventral fin)/body length between the backcross progenies and their parents. The three-dimensional spatial distribution of the backcross, S. scherzeri and the hybrid on the first three principal components did not overlap and were distinguished from each other. Discriminant analysis can clearly classify the three groups in two-dimensional. The body spots of the backcross included back saddle spots and trunk spots which can be classified into four different combinations. 45.5% of the individuals had back saddle spots, and 72.8% had hollow spots. The results can provide data for cross breeding and hybrid identification of S. chuatsi.
Application of grey topological prediction model in water quality prediction of artificial reef area in Haizhou Bay
Yuxin SHEN, Shuo ZHANG, Lizhen WU, Jikun LU, Guanghui FU
Latest Accepted  doi: 10.12131/20190171
In this study, we applied residual modified GM (1,1) model and grey topological prediction method to establish water quality prediction models based on the monitoring data of dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD5) and dissolved inorganic nitrogen (DIN) of the artificial reef area in Haizhou Bay in spring (May) and autumn (October) of 2007−2017. Then we selected the model with higher accuracy to predict the variation trend of water concentration during 2018−2022. Finally, we verified the forecast results with the meaured data of 2018. The results indicate that the grey topological model has better prediction accuracy for water quality data than the residual correction GM (1,1). The predicted results are consistent with the actual values in 2018, so the model is reliable. According to the prediction results, the DO and COD can maintain good values in 2018−2022. It is shown that the construction of artificial reef has a certain restoration effect on the water environment of the sea area, but BOD5 and DIN have a risk of exceeding the standard; and there is still a lot of research space to be further explored on improvement of grey topology model.
Extraction and antioxidant activity of protein from Grateloupia livida
Miaomiao CAI, Shengjun CHEN, Xianqing YANG, Haixia MA, Jianchao DENG, Chunsheng LI, Xiao HU, Bo QI
Latest Accepted  doi: 10.12131/20190232
With Grateloupia livida as the raw material and protein extraction rate as the index, we explored the effect of different wall-breaking techniques on their protein extraction, and optimized the ultrasonic-assisted water extraction by single-factor analysis and orthogonal test. The antioxidant activity of the crude protein that was purified by ammonium sulfate salting-out was evaluated. Results show that the highest protein extraction ratio of the swelling method, freeze-thawing method, and bead milling method were (29.66±0.86) %, (24.52±0.04) % and (26.52±0.79) %, respectively, all lower than those of ultrasonic-assisted water extraction method. The best optimal conditions of extracting protein from centipede hyoid by ultrasonic assisted water extraction (the protein extraction rate could reach 58.16%) are as follows: liquid-to-solid ratio of 160 mL·g−1, total ultrasonic time of 60 min, ultrasonic power of 1440 W and pH of 6.0. The crude protein had strong antioxidant activity at the concentration of 1−8 mg·mL−1 (its reducing power at 8 mg·mL−1 was 0.43±0.01), and the IC50 of DPPH free radicals and ABTS free radicals were 4.00 mg·mL−1 and 3.96 mg·mL−1, respectively.
Effects of dietary microalgae on growth and survival of larval development of sea urchin (Anthocidaris crassispina)
Shigai XI, Chuanxin QIN, Zhenhua MA, Gang YU, Jinhui SUN, Wanni PAN, Tao ZUO, Hongmei MA, Wentao ZHU
Latest Accepted  doi: 10.12131/20190209
To investigate the growth and survival of sea urchin (Anthocidaris crassispina) larvae, we fed six microalgal diets [Dicrateria zhanjiangensis, Chaetoceros gracilis, Pavlova viridis, Platymonas subcordiformis, Chlorella vulgaris, and mixture of C. gracilis and D. zhanjiangensis (1∶1)]. The results show that different diets had different effects on the growth and development of the planktonic larvae of the sea urchin. D. zhanjiangensis was the optimal microalgal diet. C. gracilis was the second, and then were P. viridis, C. vulgari, and mixture of C. gracilis and D. zhanjiangensis. However, P. subcordiformis was not suitable to be used as the opening bait for the sea urchin larvae rearing. In terms of baits, D. zhanjiangensis was the best, since the survival rate of the larvae could reach (23.12 ±1.8)%, significantly higher than that of other unicellular algae (P<0.05). In terms of growth rate, mixture of C. gracilis and D. zhanjiangensis was the best, since the average length of the larvae could reach (885.25±30.49) μm, significantly higher than that of the other five treatments (P<0.05). The growth of the larvae fed with P. viridis was slow at early stage with the body length of (337.98±24.56) μm, but it grew faster than the other unicellular algae at later stage with the body length of (580±32.95) μm, so P. viridis is the suitable bait for planktonic larvae of A. crassispina at later stage.
Spatio-temporal distribution and eutrophication assessment of nutrients in Daya Bay during 2009—2015
Wenchao YANG, Daojian HUANG, Jixin CHEN, Xiaoyan CHEN, Yushan WANG
Latest Accepted  doi: 10.12131/20190244
We investigated the spatio-temporal distribution characteristics and eutrophication of nutrients in Daya Bay in April and May 2009, May and June 2010, February 2012, as well as January and February 2015. Generally speaking, the contents of DIN and PO4-P increased first and then decreased. The spatio-temporal distribution of DIN and PO4-P was affected by terrestrial pollution, marine aquaculture, etc.. The nutrient concentration decreased from coastal area to open sea. The evaluation of potential eutrophication indicates that the seawater in Daya Bay experienced a process from poor nutrition to moderate nutrition and then to poor nutrition. The seawater in the functional areas of Class I was always in a state of poor nutrition. The average N/P ratio was lower than the Redfield value (16) in the monitoring period.
Effects of acute ammonia nitrogen stress on enzyme activities of gills and digest tract in juvenile mandarin fish (Siniperca chuatsi)
Weidong DING, Liping CAO, Zheming CAO, Xuwen BING
Latest Accepted  doi: 10.12131/20190188
We investigated the effects of ammonia stress on the enzyme activities in gills and digestive tract of juvenile mandarin fish (Siniperca chuatsi) with body mass of (13.31±0.49) g and body length (9.73±0.46) cm to reveal their physiological changes under the circumstances of temperature (22.0±0.5) ℃ and ammonia concentration of 48.65 mg·L−1. The results show that juveniles under acute ammonia nitrogen stress had undergone significant changes in the activity levels of Na+/K+-ATPase, respiratory metabolic enzymes and digestive enzymes. The Na+/K+-ATPase activity was significantly different from that of the control group, which first increased and then decreased with time. The activity of respiratory metabolism enzyme increased under stress. Digestive enzymes in the stomach and digestive tract were significantly affected too. AMS activity first decreased and then increased, while pepsin and LPS increased first and then decreased. The results suggest that ammonia nitrogen stress can cause a variety of impairments in the fish body, including deterioration of antioxidant system, physiological metabolism, gill tissue, respiratory function and detoxification function. In order to keep impairment less, the digestive and anaerobic metabolism enzyme activities should be activated to higher level to produce energy for the body’s resistance to stress response.
Effects of multiple environmental factors on molting death of Procambarus clarkii and countermeasures
Dongliang LIU, Jianhua HUANG, Lishi YANG, Liqi TAN
Latest Accepted  doi: 10.12131/20190128
In order to study the cause of molting death of Procambarus clarkii and its preventive measures, we raised and stressed the crayfish of different sizes by different environmental factors. The results show that the survival rate and decidua rate of P. clarkii were the highest in groups of 30 mg·L−1 Ca2+ and 15 mg·L−1 Mg2+, significantly higher than those in the contol (P<0.05), but their decidua mortalities were significantly lower than those in the control (P<0.05). When the pH value was 9.23 or the dissolved oxygen concentration was 4.5 mg·L−1, the survival rate and decidua rate were significantly lower than those in the control (P<0.05), but the decidua mortality was significantly higher than that in the control (P<0.05). The molting mortality of P. clarkii was highest when the salinity was 21 (P<0.05). Environmental factors and many other factors are the important causes of molting death of P. clarkii.
Effects of chronic ammonia stress on growth, antioxidative and immunity indices in liver of juvenile Acipenser schrenckii
Min GUAN, Dezhi ZHANG, Daming TANG
Latest Accepted  doi: 10.12131/20190191
To preliminarily reveal the physiological response of juvenile Acipenser schrenckii to chronic ammonia-nitrogen stress, we exposed the juveniles to different ammonia nitrogen concentrations (0.01, 0.5, 1.0, 2.0 and 4.0 mg·L−1) for 60 d, and investigated their growth, antioxidative and immunity indices. The results show that the weight gain rate (WGR), specific growth rate (SGR), viserosomatic index (VSI) and viserosomatic index (VSI) of the juveniles decreased gradually with the increase of ammonia concentration (P<0.05). However, there was no significant change in condition factor (CF). Among the antioxidative indices, the superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC) activity and glutathione (GSH) content in liver decreased gradually with the increase of ammonia concentration, while malondialdehyde (MDA) content increased gradually. Among the immune indices, chronic ammonia-nitrogen stress reduced the lysozyme (LZM) activity and immunoglobulin M (IgM) content in the liver significantly (P<0.05). The results suggest that the chronic ammonia stress inhibited the growth, antioxidative and immunity capacity of the juveniles significantly. Thus, in the actual breeding process of A. schrenckii, the ammonia concentration in water should be controlled at ≤0.5 mg·L−1 to avoid the adverse effects of ammonia stress.
Selection of artificial fish nest material and influencing factors of implementation effects
Yuefei LI, Weitao CHEN, Yuguo XIA, Jiping YANG, Shuli ZHU, Xinhui LI
Latest Accepted  doi: 10.12131/20190198
To determine the optimal artificial fish nest material, and to promote restoration technology of spawning grounds for fish species with adhesive eggs, we had made fish nests with six kinds of materials (Arundo donax, Miscanthus sp., Pennisetum purpureum, Livistona chinensis, simulation aquatic plants and nylon mesh) at Zhaoqing section in Xijiang River from March to May in 2019, and studied the effects of materials and environmental factors on the implementation of fish nests. Common carps (Cyprinus carpio) had strong preference for adhesion medium, and Arundo donax was the best material for making fish nests, since the eggs adhesion ratio and the number of eggs in each nest were significantly higher for Arundo donax than for the other materials (P<0.05). The eggs adhesion ratio and the number of eggs decreased with the increase of the days of entering water. The principal component analysis reveals that the days of entering water is the most important influencing factor on the implementation effect. The increase of discharge and rise of water level can promote the common carps to gather to nests and lay eggs, but the weather condition had little effect. Besides, we discussed the effect of implement time and location.
Feasibility study on recycling of grass carp feces by Pomacea canaliculate
Fang OU, Di WU, Min YIN, Zhijian WANG, Li JIN
Latest Accepted  doi: 10.12131/20190179
In order to study whether the apple snail (Pomacea canaliculate) can utilize the feces produced by the grass carp (Ctenopharyngodon idellus) effectively after feeding the water hyacinth (Eichhornia crassipes), we analyzed the growth index, body composition, digestive enzyme activity and accumulation of nitrogen and phosphorus in grass carp feces group and water hyacinth bait group, respectively. The results show that: 1) The body mass in the two groups increased very significantly after 35 d (P<0.01). Both the specific growth rate (SGR) and food conversion rate (FCR) in water hyacinth group were very significantly higher than those in feces group (P<0.01). There was no significant difference in the survival rate (SR) between the two groups (P>0.05). 2) The difference in body composition between the two groups of snails was not significant (P>0.05). 3) The activity of gastric amylase in water hyacinus group was significantly higher than that in feces group (P<0.05), and there was no significant difference in cellulase and lipase activity between the two groups (P>0.05). 4) Apple snail accumulated nitrogen and phosphorus elements in both groups without significant difference (P>0.05). In summary, the feces of grass carp can meet the basic growth requirements of apple snails and reduce the nitrogen and phosphorus contents in the water indirectly. It is suggested that apple snails can be used to reduce the pollution brought by grass carp feces in " water-water hyacinth-grass carp” farming mode.
Variation of fishing ground gravity of tuna free-swimming school caught by purse seiner in Western and Central Pacific Ocean and its relationship with southern oscillation index
Peng LI, Liuxiong XU, Cheng ZHOU, Xuefang WANG, Hao TANG, Wei LIU
Latest Accepted  doi: 10.12131/20190158
Based on the data of fishing positon, fishing date and catch of free-swimming school from the logbooks of Chinese tuna purse seine fishing fleet operating on the Western and Central Pacific Ocean during 2013 and 2017, we analyzed the relationship between monthly and yearly variation of fishing grounds gravity of free-swimming school and the south oscillation index (SOI) obtained from the US Climate Analysis Center. The results show that fishing areas where the sea surface temperature (SST) was above 29.5 ℃ occurred higher catch. The fishing ground gravity was mainly distributed between 160°E and 175°W. The gravity center had an eastward tendency from 2013 to 2015 without evident monthly variation. When SOI was positive, the " warm pool” and the gravity center of the Western and Central Pacific Ocean moved towards the west, while the gravity center moved eastwards when SOI was negative. Correlation analysis shows a significant negative correlation between SOI and the fishing ground gravity (the correlation coefficient was −0.27, P<0.05), indicating that there was a close relationship between the change of fishing ground gravity center and climate change. The study helps understand the variation law of fishing ground of tuna purse seine fishery in the Western and Central Pacific Ocean.
Spatio-temporal variation of Ommastrephes bartramii resources (winter & spring groups) in Northwest Pacific under different climate modes
Jiajia LI, Jintao WANG, Xinjun CHEN, Lin LEI, Changtao GUAN
Latest Accepted  doi: 10.12131/20190175
Ommastrephes bartramii is an oceanic species with short life cycle, whose life history and biomass are affected by environmental and climatic factors significantly. Based on the fishing logs, sea surface temperature (SST), chlorophyll (Chl-a) and Pacific decadal oscillation (PDO) data from 2004 to 2015 in the Northwest Pacific, we applied patial autocorrelation statistics, hot spot analysis and wavelet analysis to study the spatio-temporal variation of O. bartramii in that area under two climatic modes of cold and warm periods of PDO. The results show that the PDO index was positively correlated with the catch per unit effort (CPUE) and the CPUE lagged PDO for eight months. However, the conjugate period was 2−4 months under the influence of CPUE and PDO index. The distribution of fishery hotspots under different climate modes is characterized by the fact that the center of gravity of fishing ground is obviously distributed in high and low latitude direction with strong and relatively poor spatial agglomeration in warm and cold periods, respectively. It is shown that PDO index affects the spatio-temporal distribution of O. bartramii in the Northwest Pacific in different periods significantly, which provides important references for the development and utilization of O. bartramii resources.
Research progress of mechanical property of tuna longline gear
Liming SONG, Yiting LI
Latest Accepted  doi: 10.12131/20190183
The mechanical property of longline gear affects fishing efficiency and energy consumption directly. The paper summarizes relevant research methods and progress on the mechanical property of tuna longline gear, including the initial measurement at sea, the model test in the flume tank, and the numerical simulation. Results show that: 1) the theoretical analysis of mechanical property of longline gear have developed from static analysis to dynamic analysis; 2) the model test of longline could only be carried out on a small scale in order to verify the accuracy of numerical simulation analysis under specific circumstances; 3) the vertical drag coefficient (CN90) and additional mass coefficient (Cm) were determined to be 1.12 and 3, respectively. It is suggested that the future studies on longline gear mechanical property should: 1) foucus on the effects of the stiffness and damping of fishing gear materials on the numerical simulation accuracy; 2) combine the behavioral characteristics of tuna to study the hydrodynamic force after hooking and taken it into account in the model, so that the model can match the actual operation state; 3) further numerically simulate the interaction among the fishing gear, current, fishing boat, line hauler and catches.