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[Abstract](57) [FullText HTML](0) [PDF 782KB](0)
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In order to explore the law of oogenesis in Sinibrama taenitus and provide instruction for artificial reproduction, we observed the microscopic structure of its oogenesis process that was divided into five phases: phase of oogonium (Phase I), phase of single-layer follicular cell (Phase II), phase of yolk vesicle (Phase III), phase of yolk filled (Phase IV) and phase of mature oocyte (Phase V). Results of paraffin section reveals that oogonium could be distinguished as two types according to their microscopic characteristics (oogonium at early stage and mitosis). Meanwhile, the early primary oocyte was devided into Phase II, and several small nucleolus appeared at the edge of the nuclear membrane, which was regarded as the sign of beginning of little growth period. Yolk vesicles appeared in Phase III and the yolk began to accumulate and was mainly existed in the form of yolk granule when the yolk vesicles increased to 3−5 layers. After entering Phase IV, the yolk deposited into yolk platelet, and the yolk vesicles were squeezed to the perivitelline area and formed cortical vesicles. After the oocyte was mature, the area of cortical vesicles exhibited as lumps or particulates, and was dyed orange by hematoxylin-eosin staining.
[Abstract](88) [FullText HTML](0) [PDF 739KB](0)
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We investigated the effects of different levels (0%, 16.67%, 33.33%, 50% and 66.67%, represented as Diet 1# to 5# treatments) of fishmeal replacement by protein mixtures on the survival, growth, physiological metabolism and body composition of juvenile Chinese mitten crab (Eriocheir sinensis). The results show that: 1) the final body mass, weight gain rate, specific growth rate and hepatosomatic index firstly increased and then decreased with increasing dietary fish meal replacement level, and the highest values were found in Diet 2# treatment (P<0.05). 2) The highest levels of glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT) and malondialdehyde in hepatopancreas were detected in Diet 4# treatment, while Diet 1# treatment had the highest activity of superoxide dismutase (SOD) in hepatopancreas (P<0.05). The highest activity of GPT in the serum was detected in Diet 5# treatment, and the highest triglyceride (TG) content and SOD activity were detected in Diet 4# treatment (P<0.05), while the highest malondialdehyde (MDA) content was detected in Diet 2# treatment. 3) The contents of crude protein and crude lipid in the juvenile crab's body in Diet 1# treatment were significantly higher than those in the other treatments, while the highest total carbohydrate content was detected in Diet 2# (P<0.05). For the body amino acids, the highest cysteine (Cys) content was detected in Diet 4# treatment, and the highest contents of other amino acids and total amino acids (TAA) were detected in Diet 2# (P<0.05). In conclusion, excessive dietary fishmeal replacement (33%−67%) can reduce the growth performance and accumulation of nutrients in juvenile crab's body, having a negative effect on physiological metabolism. The appropriate dietary fishmeal replacement level is suggested to be about 20%.
[Abstract](108) [FullText HTML](5) [PDF 693KB](0)
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Fish anesthetic eugenol, which has high antibacterial and bactericidal effect, has presented great efficacy on the food borne pathogens as well as the pathogenic bacteria in aquaculture. In order to investigate the antibacterial effect of eugenol on the typical pathogenic bacteria in aquaculture, we studied the antibacterial effect of eugenol on Vibrio anguillarum. After 24-hour incubation, the diameter of the inhibition zone was (21.13±0.74) mm at 6 400 μg·mL–1 of eugenol, indicating that V. anguillarum was extremely sensitive to eugenol. It is shown that V. anguillarum did not grow while the eugenol concentration was over 400 μg·mL–1. Hence, the minimum inhibitory concentration (MIC) was 400 μg·mL–1 of eugenol against the bacteria. The solution in the cells of 400 μg·mL–1, 800 μg·mL–1, and 1 600 μg·mL–1 were continually incubated for 24 h after being scribbled on the plate surface. When the concentration of eugenol were over 800 μg·mL–1, no V. anguillarum grew in the plates. It is indicated that the minimum bactericidal concentration (MBC) of eugenol against V. anguillarum was 800 μg·mL–1, and eugenol has excellent antibacterial effects on V. anguillarum.
[Abstract](107) [FullText HTML](66) [PDF 1963KB](3)
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We evaluated the value of ecosystem service before and after the construction of marine ranching in Zhelin Bay by using the theory of ecosystem service. Besides, we investigated the spatial distribution characteristics of ecosystem service value in different functional areas, such as cage culture area, seaweed culture area, shellfish farming area, artificial reef area as well as enhancement and release area using ArcGIS. The results show that the ecosystem service value of Zhelin Bay marine ranching had increased from 586.13 million CNY to 673.70 million CNY during 2011−2013. However, the value structure did not change significantly, showing the highest value of provisioning service, followed by cultural service value, and relatively low value of regulating service. The spatial distribution characteristics of different functional areas in Zhelin Bay marine ranching are roughly as follows: cage culture area>seaweed culture area>shellfish farming area>artificial reef area>enhancement and release area.
[Abstract](163) [FullText HTML](41) [PDF 810KB](6)
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In order to study the difference of fatty acid and phospholipid composition in different families and species of Perciformes freshwater fish, we analyzed the fatty acids and phospholipids in muscles of Scortum barcoo, Perca fluviatilis, Lucioperca lucioperca, Micropterus salmoidesandOreochromis mossambicus by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC-ELSD). Twenty-one kinds of fatty acids had been detected in those fish. Eight kinds of common fatty acids were detected (C14:0, C16:0, C18:0, C16:1, C18:1, C18:2, C20:5 and C22:6). Polyunsaturated fatty acids (PUFA) were rich and the content was higher than 35% except for S. barcoo (26.81%). Six kinds of phosphatidylcholine were detected in those fish, including phosphatidylethanolamine (PE), sphingomyelin (SM), phosphatidylinositol (PI), lysophosphatidylcholine (LPC), phosphatidylcholine (PS) and phosphatidylcholine (PC). The PC contents in those fish muscles phospholipids were the highest, accounting for 45.84%−62.55% of total phospholipid, followed by PE and PI contents. The PS and SM contents were relatively low, accounting for only 2.19%−5.27% and 2.06%−3.65% of total phospholipids.
[Abstract](457) [FullText HTML](368) [PDF 646KB](4)
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In order to investigate the negative regulater role of myostatin (MSTN) in growth and development of adductor of Chalmys nobilis, we analyzed the promoter sequence of MSTN of C. nobilis. The results show that the promoter sequence was 1 358 bp in length, including four transcription start sites (TSS). The core promoter region was located from –100 bp to –51 bp. Two kinds of cis-regulatory element, a TATA-box (located from –92 bp to –86 bp) and two E-boxes, were detected in promoter. Potential transcription factor binding sites including MEF2, MEF3, FoxO, MTBF, MyoD and so on were found in promoter. No CpG island was found. Six luciferase expression vectors with different lengths of MSTN promoter were successfully constructed and transiently transfected into 293T cells for an analysis of the activity of dual luciferase reporter gene. It is shown that all the six promoter sequences had transcriptional activity, with PGL-534 the highest, followed by PGL-274, PGL-22 and PGL-102, and PGL-995 the lowest. There might be some binding sites of potential negative transcription factors from –216 bp to –364 bp, and potential positive transcription factors from –364 bp to –825 bp.
[Abstract](99) [FullText HTML](53) [PDF 876KB](6)
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We used histological methods to observe the gonadal development of Megalobrama terminalis, and decribed the morphology in each type of germ cell and structural feature in ovary and testis. The results indicate that M. terminalis is a one-time spawning type fish, whose ovary development type is partially synchronous. The ovary was thin or flat. The ovarian development had oogonia, monolayer follicular phase, yolk vesicle phase, yolk filling phase, maturation phase and degeneration phase. Occurrence of oocytes had undergone three stages: oogonia, primary oocytes and secondary oocytes. The nucleolar efflux phenomenon occurred in the primary oocytes of ovary from the late Stage II to the early Stage III. The testis was thin or straight with a leaflet structure. The spermatogenesis had undergone five stages: spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid and sperm. The spermatids were filled with spermatozoa and the spermatic capsules disappearred in breeding season.
[Abstract](145) [FullText HTML](76) [PDF 887KB](11)
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We investigated the composition of the stomach contents of 138 longnose lancetfish (Alepisaurus ferox) collected from September 2017 to January 2018 by the Chinese Longline Fisheries Observer Programme in the western tropical Pacific Ocean (165°45′E−178°00′W, 03°02′S−18°34′S). A total of 61 species from 44 families, belonging to six prey groups (Fish, Mollusca, Crustacea, Polychaeta, Cnidaria and Thaliacea) were identified. Cannibalism and plastic debris ingestion were also observed. The obtained values of Shannon-Wiener diversity index (H'), Pielou evenness index (J') and dominance index (D) of A. ferox's diet composition were 2.71, 0.67 and 0.12, respectively. The result of index of relative importance (IRI) analysis indicates that Mollusca was the dominant prey with IRI of 7 573.31 which accounted for 53.11% of total IRI. At family level, Sternoptychidae, Alepisauridae, Carinariidae, Pterotracheidae, Bolitaenidae, Onychoteuthidae, Oplophoridae, Platyscelidae, Eurytheneidae and Alciopidae were the most important preys of A. ferox.
[Abstract](126) [FullText HTML](67) [PDF 8418KB](7)
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Based on the data of fishery resources surveys in the Yangtze River estuary from 2012 to 2014, the spatial co-occurrence patterns and influencing factors of fish communities in that area were analyzed by using probability model and network analysis method. The results show that the fish community pattern in the Yangze River estuary is mainly the random co-occurrence of species. The influence of neutral elements was dominant in community construction, and the effect of random factors driven by environmental change on interspecific co-occurrence was greater than that of interspecific interaction. There was significant seasonal difference in the patterns of interspecific co-occurrence, which was mainly related to the seasonal changes of migratory marine fish and estuarine sediment fish. The seasonal replacement of fish species with high weighted degree and betweenness centrality might also have caused the high number of randomly associated pairs of species. It is also shown that Collikithys lucidus has strong ability to control information exchange within the community and is at the core of the fish community structure in the Yangtze River estuary.
[Abstract](135) [FullText HTML](105) [PDF 881KB](4)
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In order to study the sterilization effect of fresh tilapia fillets with slightly acidic electrolyzed water, the single factor and response surface experiment were adopted to establish the mathematical model between the factors and response values, and the best sterilization conditions were determined. The results show that the best bactericidal condition was 35.00 mg·L–1 of available chlorine concentration, 22 min for soaking time and 1∶6 (wv). Under this condition, the killing logarithm value of bacterial colony was (0.735±0.001) lg (CFU·g–1), and the bactericidal rate was (81.59±0.04)%.
[Abstract](165) [FullText HTML](146) [PDF 559KB](2)
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In order to establish a rapid and convenient method for fish species identification of Siganidae, we obtained 46 COⅠ genes from 10 species and downloaded 27 COⅠ genes from 12 species from BOLD and GenBank to study the COⅠ gene's genetic composition, intraspecific and interspecific genetic distance, codon characteristics and molecular phylogenetic tree. The results show that the average base composition of 73 COⅠ genes was T: 28.9%, C: 28.7%, A: 24.6% and G: 17.8%. The content of G+C (46.5%) was lower than the content of A+T (53.5%) and the base composition showed obvious bias. The average interspecific genetic distance was 0.098, which was 49 times the length of the genetic distance within the species (average: 0.002). The phylogenetic tree reveals that Siganus unimaculatus and S. vulpinus clustered into one branch among 19 species of basket fish. The other 17 species (89.5%) clustered in monophyletic groups at genus level. It is shown that the technology of DNA barcoding can be used for fish species identification of Siganidae.
[Abstract](98) [FullText HTML](62) [PDF 754KB](3)
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To determine the optimal dietary vitamin B2 requirement of juvenile golden pompano (Trachinotus ovatus), six experimental diets were formulated which contained 0 mg·kg–1, 4.4 mg·kg–1, 6.2 mg·kg–1, 8.0 mg·kg–1, 11.3 mg·kg–1 and 15.5 mg·kg–1 of vitamin B2. Each diet was assigned to three parallels of 25 fish [initial mass of (11.63±0.17) g] which were fed twice daily for eight weeks. The results show that the weight gain rate and specific growth rate of the fish fed with diet of 4.4 mg·kg–1 vitamin B2 were significantly higher than those of 0 mg·kg–1 group (P<0.05), and the activities of aspartate aminotransferase and alanine aminotransferase in the serum were significantly lower than those in 0 mg·kg–1 group (P<0.05). No significant effect was found on the fish coefficient, survival rate, liver vitamin B2 content, serum immune parameters, crude protein and crude fat content in whole body, moisture, crude fat and crude ash in muscle (P>0.05); the liver D-AAO activity in 6.2 mg·kg–1 group was significantly higher in 0 mg·kg–1 group (P<0.05). Broken-line model analysis estimates that the dietary vitamin B2 requirement of juvenile golden pompano is 4.23 mg·kg–1 for optimal growth, and 6.24 mg·kg–1 for maximum liver D-AAO activity.
[Abstract](108) [FullText HTML](69) [PDF 932KB](5)
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Microsatellite DNA markers were used to assess the genetic diversity of first filial generation of seven introduced Litopenaeus vannamei populations, named TH-A1, TH-A2, TH-B, US-C1, US-C2, US-C3 and US-C4, respectively. The results show that the seven populations had varying polymorphism at 12 microsatellite loci, with the mean allele number (Na) ranging from 3.333 to 6.167. The mean values of expected (He) and observed (Ho) heterozygosity were 0.477–0.670 and 0.370–0.505, respectively. The polymorphic information content (PIC) for each population varied from 0.414 to 0.623. For Hardy-Weinberg equilibrium test, 44 out of 88 exhibited significant deviation (P<0.05), which corresponded with the fact thatHe was slightly higher than Ho. Cluster analysis shows that the seven populations were clustered into three branches (TH-A1; US-C1, US-C2 and TH-A2; the rest). It is indicated that the genetic characteristics vary in different cultured populations of L. vannamei. The results provide references for further exploration of relevance between genetic characteristics and practical performance of L. vannamei.
[Abstract](152) [FullText HTML](79) [PDF 1192KB](9)
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We constructed the sRNA srvg17985 knock-out mutant in Vibrio alginolyticus ZJ-T by using homologous recombination, so as to compare the biological characteristics of growth in LBS medium, motility, extracellular protease secretion, iron utilization, antibiotic resistance and metabolism between the wild type and the mutant strains. The results show that the absence of sRNA srvg17985 did not affect the growth in LBS medium, motility, extracellular protease secretion, iron utilization, antibiotic resistance and most of the tested carbon and nitrogen sources metabolism in V. alginolyticus. However, the mutant showed better utilization of laminarin, pectin and dihydroxyaceton, and gained the ability to utilize alanine-aspartic acid (Ala-Asp) as the sole nitrogen source.
[Abstract](308) [FullText HTML](435) [PDF 633KB](4)
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In order to investigate the chloramphenicol residues in commercially available shellfish and to assess their exposure, we collected 300 shellfish samples which were determined by LC-MS/MS and analyzed by @risk software using Monte Carlo method. The daily intake and estimated dietary exposure were simulated, and the margins of exposure were calculated. The results show that 33 samples were determined to have chloramphenicol residues in 2015. The MOE value of the general population was 15 361, presenting a medium risk (according to the evaluation criteria of the Canadian Ministry of Health). The MOE value of the high exposure population was 5 208, also presenting a medium risk. In 2016, three samples were determined to have chloramphenicol residues. The MOE value of the general population was 10 3627, presenting a medium risk. The MOE value of the high exposure population was 34 722, presenting a medium risk. In 2017, no samples were determined to have chloramphenicol residues, presenting no risk.
[Abstract](155) [FullText HTML](70) [PDF 800KB](5)
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The transcripts of Micropterus salmoides were obtained by RNA-seq technology to conduct a transcriptomic analysis. A total of 35 659 unigenes were generated by de novo assembly with an average length of 738 bp and N50 of 1 052 bp. The unigenes were assessed for length distribution and GC content. The sequencing data were of high quality and reliability. A total of 15 832, 21 279, 14 524, 16 973, 15 024 and 11 185 unigenes were annotated from the KOG, Nr, Pfam, Swiss-Prot, GO and KEGG databases, respectively, among which 5 617 were annotated in all the databases and 17 253 were annotated in at least one database. Blasted with KEGG pathway, 11 185 unigenes were annotated, belonging to 267 categories. Of all the pathways, the number of unigenes joining in the signal transduction was the most (1 349, 12.06%). Finally, 4 030 SSRs were identified. The results provide rich data to understand transcriptome information of M. salmoides and lay the foundation for further research on functional gene cloning, genomics, genetic diversity analysis, molecular marker exploitation and genetic improvement in M. salmoides.
[Abstract](147) [FullText HTML](127) [PDF 1185KB](8)
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To compare the physiological and ecological characteristics of inoculant of photosynthetic bacteria and Rhodopseudomonas palustri, we analyzed the degradation effects of the inoculant PG and the strain PSB-1 with different initial amounts of bacteria on ammonia nitrogen ( \begin{document}${\rm NH}^+_4$\end{document} -N), nitrite nitrogen ( \begin{document}${\rm NO}^-_2$\end{document} -N), nitrate nitrogen ( \begin{document}${\rm NO}_3^-$\end{document} -N) and phosphate ( \begin{document}${\rm PO}_4^{3-}$\end{document} -P) in the experimental water. Then we studied the dominant bacteria composition of inoculant of photosynthetic bacteria PG, as well as the number of bacteria and microbial community composition in the experimental water at the end of the experiment by high-throughput sequencing. The results show that the inoculant PG group had certain degradation effects on \begin{document}${\rm PO}_4^{3-}$\end{document} -P, \begin{document}${\rm NO}_3^-$\end{document} -N and \begin{document}${\rm NO}_2^-$\end{document} -N in the experimental water. The maximum degradation rates of PG for \begin{document}${\rm PO}_4^{3-}$\end{document} -P, \begin{document}${\rm NO}_3^-$\end{document} -N and \begin{document}${\rm NO}_2^-$\end{document} -N were 40.98%, 28.28% and 20.12%, respectively. Moreover, the strain PSB-1 group only had certain degradation effect on \begin{document}${\rm NO}_2^-$\end{document} -N and \begin{document}${\rm PO}_4^{3-}$\end{document} -P. The maximum degradation rates of PSB-1 were 14.19% and 9.88%, respectively. The dominant bacteria of the inoculant PG belonged to Rhodopseudomonassp.. After 7 d of experiment, the number of bacteria and microbial community structure in the experimental group changed, and the number of bacteria in the water increased, forming a microbial structure with heterotrophic bacteria as the dominant bacteria. It is indicated that the inoculant of photosynthetic bacteria PG has better effect on the degradation of water quality factors than R. palustris PSB-1. However, there is a certain gap between both things and the reported degradation efficiency of photosynthetic bacterial strains.
[Abstract](127) [FullText HTML](77) [PDF 546KB](15)
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Grateloupia, 42 species reported in China, are economic red algae which are widely applied in food, chemical industry and medicine (detoxication, expelling parasite, antioxidant, anticoagulant, antitumor and antioxidation). The paper reports on the research progress in the classification, reproduction, physiology, ecology and breeding, as well as points out the problem of utilization of Grateloupia, providing references for the breeding and utilization of Grateloupia.
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2018, 14(6): 0-0.
[Abstract](79) [PDF 768KB](6)
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2018, 14(6): 1-9.   doi: 10.12131/20180106
[Abstract](127) [FullText HTML](74) [PDF 948KB](15)
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We estimated the interannual change (size composition, growth, mortality and maturity in biological traits) of Decapterus maruadsi in Beibu Gulf based on the bottom trawls survey data during 1992−1993 (1992), 1998−1999 (1998), 2006, 2007, 2008−2009 (2009), 2010 and 2011−2013 (2012). Results show that: 1) The dominant body length groups decreased from 130−170 mm in 1992 to 110−140 mm in 2007, then showed an increasing trend, to 120−130 mm and 140 −170 mm in 2012. 2) The average body length decreased from 160.23 mm in 1992 to 139 mm in 2007, then increased to 149 mm in 2012. 3) The body length at 50% sexual maturity (L50) and age at 50% sexual maturity (A50) presented a similar trend with the average body length, decreasing from 180.16 mm and 1.860 in 1998 to 174.91 mm and 0.888 in 2007, respectively, then increased to 180.87 mm and 2.538 in 2012, respectively. 4) However, the growth coefficient (K) decreased gradually after increasing from 0.39 in 1992 to 0.72 in 2007, then decreased gradually to 0.5 in 2012. 5) The total mortality coefficient (Z) has been increased since the 1990s, reaching the maximum of 2.77 in 2009, then decreased to 1.68 in 2012. The variation trend of the exploitation rate (E) was similar with Z, and the E in 2010 was similar with that in early 1990s.
2018, 14(6): 10-16.   doi: 10.12131/20180097
[Abstract](145) [FullText HTML](64) [PDF 793KB](17)
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Landmark-based morphometric analysis was first used to identify the variation in the otolith and stock connectivity of Coilia mystus and C. grayii from the Pearl River estuary and Jiulong River estuary. Six landmarks in the outline of otolith and four landmarks in the sulcus were selected to extract the geometric morphometric information of otoliths. Discrimination analysis indicates that both intra-and inter-species distinguishing ratios of the two Coilia fish from two different waters were 100%. Among the 10 landmarks, those in the sulcus had main contribution (76.1%) in explaining the main source of morphological variation, while those in the outline of otolith just had 23.9%. The difference of inter-species shows that the sulcus of C. mystus was wider than C. grayii. Meanwhile, the difference of intra species shows that the C. grayii from the Pearl River estuary, had a narrower sulcus than those from the Jiulong River estuary, but the two stocks of C. mystus from these two waters were the opposite. It is revealed that the investigated stocks of either C. mystus or C. grayii from the Pearl River estuary and Jiulong River estuary are separated, which means that they may belong to different geographical stocks.
2018, 14(6): 17-26.   doi: 10.12131/20180077
[Abstract](93) [FullText HTML](89) [PDF 6526KB](3)
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In order to find out the influence law and mechanism of artificial reef on local tidal dynamics and other factors, according to the 25-hour continuous observation flow velocity and water level data of two stations in Dongshanhai artificial reef in July 2016, combining with numerical simulation method, we analyzed the effects of artificial reef on tidal power in the reef area and surrounding sea areas. With the simulation results before and after the reef construction, we obtained the variation trend of factors such as tidal current. The results show that the model simulation results fit well with the measured values. The artificial reef area had barely no effect on the tide constants and tidal characteristics in the survey area after completion. Some of the tidal current ellipsed in the artificial reef area changed direction and turned, and there was barely no influence outside the reef area. After the reef was built, the direction of the residual current within the reef area changed little, and the overall residual current of the reef area showed a decreasing trend towards the south. The horizontal flow field near the reef area changed significantly, but the influence in outer area of the reef was limited. There was an obvious upwelling flow in the inflow area of the reef, and the maximum bottom upwelling flow reached 1.2 cm·s–1 at the time of the tide surge, while the downwelling flow appeared at the back of the reef area.
2018, 14(6): 27-33.   doi: 10.12131/20180049
[Abstract](96) [FullText HTML](59) [PDF 1040KB](6)
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We studied the otolith length, width, perimeter and other morphological parameters of 106 samples of Nemipterus virgatuscollected from the continental shelf of northern South China Sea during August, 2014 to February, 2015. Results show no significant difference between female and male in otolith morphological characteristics (P>0.05). There was significant difference between left and right otolith in otolith width, area and ratio of length-width (P<0.05), but no significant difference in otolith length, maximum radius, minimum radius, perimeter, area of minimum circumscribed rectangle and ratio of radius (P>0.05). According to principal component analysis, the otolith length, width, maximum radius, minimum radius, perimeter, area, area of minimum circumscribed rectangle and ratio of radius were the main morphological indicators ofN. virgatus otolith. The relationship among main otolith morphological characteristics and body length and body mass was fitted optimally by polynomial function.
2018, 14(6): 34-42.   doi: 10.12131/20180090
[Abstract](96) [FullText HTML](47) [PDF 1050KB](4)
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We analyzed the acoustic spectrum of Bahaba taipingensis by monitoring its sound with passive acoustic method to provide basic data for the non-destructive investigation method, underwater noise environment analysis and sounding behavior of B. taipingensis. We carried out acoustic monitoring on 96 individuals of B. taipingensis by microMARS acoustic recorder in the indoor aquarrium and the two outdoor pools of Dongguan B. taipingensis Nature Reserve from March to May in 2017 (two periods and each period had 7 days and nights). We had monitored 246 sounds in total, belonging to seven types (drum sound, humming sound, cracking sound, clacking sound, bird sound, cha goo sound and other sounds). No significant difference was observed in the number of sounds between day and night. The drum sound was the main sound of B. taipingensis (175 times). The drum sound was composed of 1−3 pulses, being dominated by a single pulse type of drum (139 times). The drum sound had some sine shaped waveform (energy: 0−1 000 Hz), and its voiceprint was parallel to the timeline. The drum sound's spectral frequency peak ranged from 50 Hz to 140 Hz. The energy distribution of cracking sound was similar to that of drum sound (0−1 000 Hz), while the spectral frequency peak was 180−190 Hz. The energy distribution and frequency of the humming sound, cracking sound, birds sound and cha goo sound were both at low frequency (0−1 000 Hz) and high frequency (3 000−12 500 Hz). The pulse length, width and interval of drum sound were 67−1 333 ms, 35−733 ms and 0−1 130 ms, respectively (the average values were 279 ms, 70 ms and 183 ms, respectively). The length of drum sound and the pulse interval increased with increasing number of pulse of sound signals, while the pulse width decreased.
2018, 14(6): 43-51.   doi: 10.12131/20180114
[Abstract](93) [FullText HTML](61) [PDF 1007KB](6)
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To determine the optimal feeding density of rotifer and weaning time for Lutjanus erythopterus larvae and juveniles, we studied the impact of different rotifer feeding densities on the growth, survival and food selectivity for juvenile L. erythopterus. Then we investigated the effect of weaning time [13 dph (days post hatching, W13), 16 dph (W16), 19 dph (W19) and 22 dph (W22)] on the rearing performance of larval and juvenile L. erythopterus by using the evaluation indicators of growth, survival, RNA/DNA ratio and epithelial cell height of the digestive tract. The results show that the feeding density of rotifer affected the ingestion, food selection, growth and survival rate of L. erythopterus juveniles significantly. When the feeding density of rotifer was 10–20 ind·mL–1, there was no significant difference in the growth and survival rate of the juveniles, but significantly higher than treatment groups of 1 ind·mL–1 and 30 ind·mL–1. In the weaning experiment, the growth and survival rates of W19 and W22 groups were significantly higher than those of the other two groups, and the W13 treatment group had the lowest RNA/DNA ratio. At 22 dph, the height of the epithelial cells of digestive tract was significantly lower in the W13 and W16 groups than in the other two groups. It is indicated that the rotifer density had significant impact on the food selectivity of L. erythopterus during mixed feeding period of rotifers and Artemia nauplii. The rotifer density of 10–20 ind·mL–1 is recommended for the initial feeding period of L. erythopterus, and the weaning of L. erythopteruscan be started on 13 dph, but the best timing was 16–22 dph.
2018, 14(6): 52-58.   doi: 10.12131/20180100
[Abstract](128) [FullText HTML](67) [PDF 704KB](11)
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To determine the appropriate anesthetic method and dose for juvenile Micropterus salmoides in laboratory, we compared the hydrostatic anesthesia effects of two common fish anesthetics (MS-222 and eugenol) on the juveniles with different concentrations (40 mg·L–1, 50 mg·L–1, 60 mg·L–1, 70 mg·L–1, 80 mg·L–1, 90 mg·L–1, 100 mg·L–1 and 8 mg·L–1, 10 mg·L–1, 12 mg·L–1, 14 mg·L–1, 16 mg·L–1, 18 mg·L–1, 20 mg·L–1). The results show: 1. With increasing concentrations of the two anesthetics, the anesthetic time shortened but the recovery time prolonged. 2. The optimal anesthetic concentrations of MS-222 and eugenol were 70 mg·L–1 and 16 mg·L–1, respectively, while the optimal anesthetic transportation concentrations of the two anesthetics were 50 mg·L–1 and 10 mg·L–1, respectively. Then we carried out an experiment of 10-hour anesthesia transport under the optimal anesthetic concentrations of MS-222 and eugenol , and the survival rate during the transportation and after 24 h of recovery for the anesthesia group were both 100%, significantly higher than those for the non-anesthetic transport group (P<0.05). The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels increased significantly in the anesthesia transport group compared with those in the non-anesthetic transport group and hydrostatic control group (P<0.05). The ALT and AST levels in the MS-222 anesthesia group were significantly higher than those in the eugenol anesthesia group (P<0.05).
2018, 14(6): 59-65.   doi: 10.12131/20180064
[Abstract](91) [FullText HTML](180) [PDF 568KB](4)
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Taking black sea bream (Sparus macrocephlus) as object, we investigated its recovery level of immune and metabolic enzymes in serum after exhaustive exercise. Results show significant change in the LD and GLU concentrations as well as the activities of AST, ALT, SDH, LDH, PK and HK for juvenile black sea bream (length of 8.9−9.9 cm) with different recovery time after exhaustive exercise (P<0.01). At 0th hour after exhaustive exercise, the activities of LD, GLU, AST, ALT, SDH, LDH, PK and HK increased significantly (P<0.05). At 4th hour after exhaustive exercise, the LD concentration in the serum almost recovered to the control group's level (P>0.05). At 16th hour, the activities of SDH, HK, PK and AST recovered to the control group's level (P>0.05) while the GLU concentration and ALT activity were still lower than the control group's level (P<0.05). It is revealed that exhaustive exercise enhanced the oxidation resistance and aerobic metabolism of juvenile black sea bream within 4-hour stress response of post-exercise, and the fish could do exhaustive exercise again after 4 h, but the blood glucose test shows that the anaerobic metabolism tolerance decreased thereafter.
2018, 14(6): 66-73.   doi: 10.12131/20180075
[Abstract](108) [FullText HTML](80) [PDF 810KB](4)
Abstract:
We observed the embryonic, larval and juvenile development of hybrid of Schizothorax wangchiachii and Percocypris pingipingi via dry artificial reproduction, so as to provide basic data for cross breeding and variety selection. The results show that the F1 hybrid by S. wangchiachii (♀) and P. pingipingi (♂) embryos developed well at water temperature of (14.5±1.0) ℃ and pH of 8.10−8.81. The fertilization rate was 95.33%, and the hatching rate was 71.12%. The fertilized eggs were hatched within 144.33 h, and the sum effective accumulative temperature was 2 092.79 h·℃. Under similar conditions, the embryos grew faster than the parents, and the formation order of each organ was different from that of the parents. The larvae grew well, but the developmental speed and growth rate were slower than those of the father. Under the same experimental conditions, the F1 embryos of P. pingipingi (♀) ×S. wangchiachi (♂) were unable to develop normally, and the time required for development to the gastrula period was 51.25 h, and the required accumulated temperature was 743.13 h·℃. The mortality rate of the end of the gastrointestine was 85.83%, and only 12 embryos hatched in the end with all larvae deformed. All larvae died after 3 d. The results show that it is feasible to cross between S. wangchiachii (♀) and P. pingipingi (♂).
2018, 14(6): 74-80.   doi: 10.12131/20180086
[Abstract](119) [FullText HTML](77) [PDF 539KB](5)
Abstract:
In order to explore the effects of HSC70-1 gene on growth traits of largemouth bass (Micropterus salmoides) and develop growth-related SNPs, we obtained the cDNA of coding region and the complete sequence of HSC70-1 gene by PCR amplification. The encoding region cDNA sequence of HSC70-1 gene was 1 953 bp, encoding 650 amino acids. Its complete sequence was 3 390 bp in length, consisting of 8 exons and 7 introns. We screened four SNPs (at 821, 1 105, 1 200 and 2 804 bp on the introns) by direct sequencing, and found that the individuals with CC genotype of C-821G site had significantly higher values of body mass or total length than those with CG or GG genotypes (P<0.05). At the position of A-2804T, the individuals with TT genotype had significantly higher values of body mass or total length than those with AT or AA genotypes (P<0.05). The other two SNP loci were not significantly correlated with growth traits (P>0.05). The optical combined genotype ofHSC70-1 gene was D1 (CC--CCTT), which had significantly higher values of body height or total length than those with D5. The growth-related C-821G, A-2804T and D1 can be useful candidate molecular markers for largemouth bass molecular marker-assisted selection.
2018, 14(6): 81-88.   doi: 10.12131/20180056
[Abstract](100) [FullText HTML](90) [PDF 1005KB](3)
Abstract:
To provide basic experimental data for developing protocols to prevent and cure the disease caused by Vibrio harveyi, we collected the compound of Fructus mume water extract and antibiotics, which has synergism of antibacterial activity against V. harveyi. First, we plotted the standard curves of concentration logarithms versus inhibitory zone diameters of the test drugs, and used comprehensive combination experimental design method to screen the antibiotics which had synergism effect with F. mume water extract. Then, we applied central concentration design (CCD) with response surface methodology (RSM) to investigate the interaction among F. mume water extract and antibiotics against V. harveyi and to find their optimum combination. Results show that significant synergism existed between F. mume water extract and tetracycline, oxytetracycline, aureomycin and deoxytetracycline. RSM results indicate that the synergism between F. mume water extract and oxytetracycline contributed to the most significant effect on the antibacterial activity against V. harveyi. However, antagonism effect existed between oxytetracycline and aureomycin, and between oxytetracycline and deoxytetracycline. The optimum ratio of F. mume water extract, oxytetracycline, aureomycin and deoxytetracycline was 45∶0.12∶0.00∶0.00 (mg·mL–1). For this optimum combination, the predictive inhibitory zone diameter was 18.54 mm. According to cup method, agar diffusion method with three replicates, the practical maximum inhibitory zone diameter was (19.03±0.07) mm, and the relative error between predictive values and actual values was 2.6%. Thus, RSM is a reliable approach to describe the relationship among test drugs and inhibitory zone diameter.
2018, 14(6): 89-98.   doi: 10.12131/20180034
[Abstract](95) [FullText HTML](533) [PDF 842KB](4)
Abstract:
In order to fully understand the pesticide residues of river crab (Eriocheir sinensis) cultured in rice fields in northeast China, a total of 42 pesticide residues were determined in E. sinensis obtained from major integrated rice-crab aquaculture field in Jilin, Liaoning and Heilongjiang Provinces in northeast China by gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry. Index of food safety (IFS) method was used for health risk assessment. Fourteen pesticides, such as β-HCH, p, p′-DDE, oxyfluorfen, butachlor, acetochlor and atrazine were found in the samples. The other 28 pesticides were not detected. β-HCH (89.3%) and p, p′-DDE (82.1%) were the most frequently detected residues. The maximum residues were found in oxyfluorfen (256 μg·kg–1) and butachlor (185 μg·kg–1). The IFS value of detected pesticides were all less than 1 and the average \begin{document}$\overline {{\rm{IFS}}}$\end{document} was 0.000 7. The health risk of pesticide residues in river crab from rice field in northeast China is at safe level.
2018, 14(6): 99-104.   doi: 10.12131/20180055
[Abstract](99) [FullText HTML](56) [PDF 472KB](3)
Abstract:
In order to evaluate the nutritive value of Grateloupia livida and improve its comprehensive utilization rate, we determined the composition of the basic nutrients, amino acids, fatty acids and minerals of G. livida. The results show that the mass fractions of crude protein, crude fat, ash and crude fiber were 12.28%, 0.18%, 13.32% and 1.80%, respectively. Seventeen kinds of amino acids were found which contained eight kinds of essential amino acids, and the limiting amino acid was tryptophan. G. livida contains 15 kinds of fatty acids, such as linoleic acid, arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid which have important physiological functions. The results indicate that G. livida is nutritive and rich in Mg, Ca, Fe, Zn and Cu.
2018, 14(6): 105-112.   doi: 10.12131/20180074
[Abstract](84) [FullText HTML](41) [PDF 648KB](4)
Abstract:
The myofibrillar proteins extracted from purple back flying squids (Symplectoteuthis oualaniensis) were glycosylated with alginate oligosaccharide, and the glycosylated protein was simulated in vitro hydrolyzed by pepsin and pancreatin. The antioxidant properties and amino acids contents were analyzed. Results show that the free amino acids concentration decreased significantly after glycosylation, which was more obvious for the first 12 h, indicating the reaction occurred between protein and saccharides. The free radical DPPH and reducing power of both protein and the in vitro digests increased after glycosylation greatly (P<0.05). Therefore, the glycosylation increased the antioxidant properties of protein. While the radical scavenging ability and reducing power decreased after hydrolysis. The SDS-PAGE indicates that glycosylated protein showed bands with greater molecule weight, and its hydrolysates had more peptides with lighter molecule weight, which suggests that the glycosylation process promoted protein hydrolysis. The essential amino acids contents decreased while hydrophobic amino acids contents increased for the glycosylated protein hydrolysates.
2018, 14(6): 113-117.   doi: 10.12131/20180030
[Abstract](87) [FullText HTML](50) [PDF 493KB](3)
Abstract:
In order to clarify the occurrence and epidemic rule of Parkin's disease in shellfish, we investigated the infection of parasitic protozoa (Perkinsus spp.) on the common shellfish hosts along the coastal area of Guangxi Province, and studied the epidemiology of Perkinsus spp. on two locally cultured bivalves (Crassostrea hongkongensis and Ruditapes philippinarum). The results show that among the 14 investigated shellfish species, 13 were infected by P. olseni, 8 by P. beihaiensis, and 7 by P. olseni and P. beihaiensis at the same time (the same type of shellfish was at most infected with one kind of parasitic protozoa). The prevalence of P. olseni in Soletellina acuta, Callista erycina, R. philippinarum and Scapharca subcrenata was significantly higher than that in the other 10 species. The prevalence of P. beihaiensis in C. hongkongensis and Perna viridis was significantly higher than that in the other 12 species. The prevalence of P. beihaiensis was significantly higher than that of P. olseni in C. hongkongensis. The prevalence of P. olseni was significantly higher than that of P. beihaiensis in R. philippinarum. The prevalence of Perkinsus spp. varied in different shellfish species and coastal areas.
2018, 14(6): 118-127.   doi: 10.12131/20180037
[Abstract](178) [FullText HTML](168) [PDF 4243KB](16)
Abstract:
There are abundant pelagic fishery resources in the deep sea of the South China Sea (SCS). However, since the fishery resources in the coastal and shelf area of northern SCS have long been overfished, the pelagic fishery resources in that area have not been utilized adequately. Lack in assessment for pelagic stocks limits the rational use of the pelagic fisheries resources. In order to obtain the information of exploring potential, fishing ground and catching season of pelagic fisheries resources, the South China Sea Fisheries Research Institute has been carrying out continuous pelagic fishery resources surveys in the vast deep sea area of SCS since 2011. In spring 2011, for the first time, fisheries acoustics detection and light-falling sampling were synchronously used to investigate pelagic fishery resources in the deep sea of SCS. Based on the acoustics-light falling net sampling technique, the abundance and distribution of the major category of fishery stocks were evaluated. Many large fishing grounds were discovered, which confirms great exploring potential of pelagic fisheries resources in the deep sea of SCS. This paper reviews the latest results in the assessment of pelagic fisheries resources in the deep sea of SCS, and summarizes the existing problems and future research direction.
Display Method:
Latest Accepted  doi: 10.12131/20180222
[Abstract](47)
Abstract:
In order to study the rationality of the release of the Portunus trituberculatus in Zhoushan fishing ground, Yangtze River estuary fishing ground and their adjacent waters in recent years, we analyzed the energy flow characteristics of the ecosystem in that sea area and estimated the proliferation capacity ofP. trituberculatus based on the fishery resources survey data from 2006 to 2014 by constructing the Ecopath model. The results show that the ecosystem was mainly made up by benthos, and shrimps, Trichiurus leptures andP. trituberculatus had higher food utilization rates. The food utilization rates ofChelidonichthys kumu and Trachurus japonicuswere relatively low. Four trophic levels can be divided in the survey area, and P. trituberculatus is a medium trophic organism. The total catch was 1.614 t·km–2 (the catch of P. trituberculatus was 0.057 8 t·km–2). The total consumption was 280.744 t·km–2. The total export was 790.396 t·km–2. The total production was 959.3 t·km–2. The biomass of P. trituberculatus was 0.125 t·km–2. The ecological capacity was 1.125 t·km–2. The proliferation capacity was 1 t·km–2. It is shown that the primary productivity of the survey area is high, and the marine organisms are distributed in the second and third trophic scales with relatively low ecosystem maturity. There is still a certain releasing space.
Latest Accepted  doi: 10.12131/20180185
[Abstract](85)
Abstract:
We isolated 14, 4 and 2 strains of Streptococcus agalactiae from naturally infected adult and juvenile tilapia as well as tilapia naturally carrying S. agalactiae, respectively. The clinical signs and anatomy changes of adult tilapia are as follows: erratic swimming, congestion of brain, eyeballs, sputum and fins, exophthalmia, corneal opacity and swelling of visceral organs, which were characterized by histopathological changes with tubular hyaline degeneration, meningitis and epicarditis. The clinical symptoms of juvenile tilapia are not obvious, but some of the internal organs showed swelling and congestion, characterized by main histopathological features of hemorrhage of spleen vascular area, degenerated renal tubular epithelial cells and milder inflammatory response in brain tissue. In addition, eosinophil infiltration was found in the lamina propria of tilapia and in the liver of juvenile fish. It was observed that S. agalactiae proliferated in the brain and heart of adult fish and in the liver of juvenile tilapia, respectively. The clinical symptoms and histological lesions in tilapia carrying S. agalactiae were not obvious. The results of PCR detection show that all the S. agalactiae strains had the same virulence gene profiles, but there were significant differences in pathological damages among adult fish, juvenile fish and tilapia carrying S. agalactiae.
Latest Accepted  doi: 10.12131/20180197
[Abstract](63)
Abstract:
In order to investigate the size selectivity of codend of shrimp beam trawl for Metapenaeus ensis, with the covered codend method and trouser trawl method, we carried out fishing experiments on two traditional diamond-mesh codends (D25 and D30), and six novel combined square-mesh and diamond-mesh codends (S35+D18, S25+D25, S30+D25, S35+D25, S35+D30 and S35+D35) in the South China Sea during 2014-2017. We used maximum likelihood method to estimate the selective parameters at haul by haul level and combined haul level with the logistic equation. The results indicate that the D25 and D30 codend were nearly nonselective for M. ensis. In experiments of covered codend method, the mean 50% retention lengths (L50) of M. ensis for the S35+D18, S25+D25, S30+D25 and S35+D25 codend were 51.52, 60.84, 63.21 and 64.53 mm, respectively, and the mean selection ranges (SR) were 16.48, 14.31, 12.84 and 9.75 mm, respectively. In the experiments of trouser trawl method, the mean L50s for the S35+D25, S35+D30 and S35+D35 were 75.43, 82.38 and 95.39 mm, respectively, and the mean SRs were 6.93, 6.39 and 20.44 mm, respectively, and the mean relative fishing intensities (p) were 0.51, 0.52 and 0.64, respectively. Considering the first mature length of M. ensis (80 mm) in the South China Sea, economical efficiency of fishing and selective properties of codends, it is suggested that the S35+D30 has the best selectivity. The results are benefit for the management of shrimp beam trawl and sustainable harvest of the fishery resources of M. ensis in the South China Sea.
Latest Accepted  doi: 10.12131/20180178
[Abstract](77)
Abstract:
In order to study whether aeration will promote the occurrence of cyanobacterial (Microcystis spp.) blooms in aquaculture ponds, we conducted an experiment (a treatment group and a control group) in a greenhouse during summer, without sediment addition and three replicates of glass tanks. The control group was not aerated, but the treatment group was aerated with common aeration intensity for aquaculture ponds. Inorganic nitrogen and phosphorus nutrients were added to both the control and the treatment twice. The initial phytoplankton was dominated by green algae, then Microcystis gradually appeared both in the two groups, and then became the most dominant species at later stage of the experiment [average wet mass of 36.28~75.81 mg·L–1]. The dissolved oxygen mass concentration in the control was significantly higher than that in the treatment (P<0.05); however, there was no significant difference between the two groups (P>0.05), including chlorophylla, total algal wet mass, cyanobacteria wet mass, green algae wet mass, proportion of Microcystis to the total wet mass, as well as zooplankton contents. It is indicated that aeration disturbance in aquaculture ponds had no direct influence on the occurrence of Microcystis dominance, which can appear either at the presence or absence of aeration disturbance, and the aeration disturbance mainly changes the position of Microcystis colonies in the water column.
Latest Accepted  doi: 10.12131/20180203
[Abstract](75)
Abstract:
We selected 12 microsatellite primers with specificity and polymorphism from 51 microsatellite primers from GenBank by using an automatic nucleic acid protein analysis system. Fluorescent-labeled primers were synthesized to amplify the three cultured populations of M. salmoides from the main culture area of Guangdong. The results show that among the 12 microsatellite loci, three of them were highly polymorphic, four were moderately polymorphic, and the remaining five showed low polymorphic. The genetic diversity of these three populations was low, and the expected heterozygosity (He) was 0.312 5, 0.360 6 and 0.328 4, respectively. Genetic differentiation index and AMOVA analysis among populations show that the genetic differentiation among populations was low, and 85.83% of genetic variation came from difference among individuals within populations. Genetic distance analysis shows that the genetic distance was small and genetic similarity was rather high among the three cultured populations. Genetic structure analysis shows that the three cultured populations origined from the same subgroup. The results suggest that the genetic diversity of the cultured population of M. salmoides in China has decreased significantly at present. Therefore, great attention should be paid to improving and maintaining genetic diversity of the population during the breeding process.
Latest Accepted  doi: 10.12131/20180226
[Abstract](114)
Abstract:
In order to provide basic data for intensive processing of oysters, we compared the nutritional components and flavor characteristic of cultivated oysters from different coastal areas of China. Results show that the contents of nutrient substances in the oysters, including protein, fat, ash, glycogen and taurine, were significantly different (P<0.05). It was found that the Zn content in the oysters was the highest among all the detected elements which had significant regional difference (P<0.05). The contents of Zn, Cu, Cd and Pb in the oysters from Shantou were significantly higher than those from the other areas (P<0.05). For the taste-active components, there were abundant delicious free amino acids, flavor-enhancing nucleotides and betaine in the oysters, most of which showed significant difference in different areas and among varieties (P<0.05). The betaine content in the oysters from the north was generally greater than those from the south (lowest inCrassostrea hongkongensis but highest in C. angulata). The main flavor components of oysters from different sea areas were significantly different, and the key volatile flavor compounds (relative odor activity value, ROAV≥1) were aldehydes. Among them, 1-octen-3-one showed the greatest contribution to the overall flavor of oysters from Shantou, but (E,Z)-2,6-nonadienal was the most important flavor substance in the oysters from the other sea areas. It is revealed that significant difference existed in the contents of nutrient composition, taurine, taste substance and volatile flavor composition in oysters from different regions (P<0.05).
Latest Accepted  doi: 10.12131/20180193
[Abstract](128)
Abstract:
In order to explore the regulation rule of spermatozoa motility of Schizothorax irregularis, and to improve fertilization rate and fingerling production efficiency, we applied a significance test and response surface method to study the single regulation and compound regulation of glucose, glycerol and three salts on sperm motility of S. irregularis. The results show that the maximum fast movement time of S. irregularis spermatozoa was 37.00 s when glucose was 433.7 kPa, significantly higher than those in the other groups (P<0.01). The maximum fast movement time ofS. irregularis spermatozoa was 32.33 s when glycerol was 506.7 kPa, without difference with that in 416.3 kPa group, but was significantly higher than those in the other groups(P<0.05). The maximum fast movement time ofS. irregularisspermatozoa was 35.00 s when sodium chloride was 431.4 kPa, without difference with that in 348.8 kPa group, but was significantly higher than those in the other groups (P<0.05). Potassium chloride had no obvious effect on activating spermatozoa, and magnesium chloride solution showed inhibition effect for spermatozoa. An equation about the relation of fast movement time and glucose, glycerol and sodium chloride was established. The linear and quadratic effects of the equation were very significant (P<0.01), and interaction effect was significant (P<0.05). The optimizied formulation of model was sodium chloride of 164.78 kPa, glycerol of 216.55 kPa, glucose of 208.43 kPa, and the theoretical FT was 68.24 s. The results indicate that the optimized activator formula by response surface methodology can improve the motility ofS. irregularis spermatozoa.
Latest Accepted  doi: 10.12131/20180165
[Abstract](131)
Abstract:
To explore the mechanism of the quality improvement of the low-salt silver carp surimi gel by ultra-high pressure processing (UHPP), we compared the differences of water state and microstructure among high-pressure processed low salt surimi gels (300 MPa, 1.5% NaCl), atmospheric low salt surimi gels (0.1 MPa, 1.5% NaCl) and controlled surimi gel (0.1 MPa, 2.5% NaCl) by analyses of low field nuclear magnetic resonance (LF-NMR), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The results of DSC show that the freezing point of frozen water decreased but the bound water content increased significantly from 10.89% to 17.58% after UHPP treatment (P<0.05). The LF-NMR results demonstrate that the spin-spin relaxation time (T21, T23 and T24) of low-sodium surimi gels after UHPP treatment decreased significantly (P<0.05), and the proportion of non-flowing water increased by 9.39% (from 67.29% to 76.65%). In addition, a smooth, uniform and denser network structure was achieved for low-sodium surimi gels at 300 MPa. Therefore, UHPP treatment (300 MPa, 10 min) can increase the bound water content and microstructure of low salt surimi gel.
Latest Accepted  doi: 10.12131/20180149
[Abstract](112)
Abstract:
Based on the data of marine fishing production structure in the South China Sea during 2015—2017, we investigated the effect of summer fishing moratorium by studying the indicators such as daily yield, daily output value, catch per unit effort (CPUE) and trawl fishing rate before and after summer fishing moratorium, with a differential test and growth rate analysis. The results show that the daily yields of fishing boats after summer fishing moratorium increased by 19.21%, 49.99% and 114.64% in 2015, 2016 and 2017, respectively, compared with those before the moratorium. The average daily output values increased by 0.40%, 16.06% and 49.14% respectively. CPUE increased by 7.12%, 73.30% and 110.90%, respectively. The fishing moratorium system had a significant impact on the daily output of fishing vessels (P<0.05), but a limited impact on the daily output value, CPUE, fishing rate and fishing structure (P>0.05). To sum up, the effect of summer fishing moratorium in the South China Sea affects the yield increment significantly, but affects the resource community structure not so much. The effect of in 2017 is better than that in 2015 and 2016.
Latest Accepted  doi: 10.12131/20180143
[Abstract](121)
Abstract:
In order to assess the effects of the construction of Zhenlin Bay marine ranching in the eastern Guangdong, we compaird the variation in sea surface temperature (SST), chlorophyll a concentration (Chl-a), catch per unit effort (CPUE), biodiversity, biomass and density of zoobenthos during the pre- (August in 2011) and post- (August in 2013) marine ranching in Zhelin Bay, based on satellite remote sensing and survey data. Results show that the N/P ratio was nearly16, and Chl-a increased from 7.5–12.3 mg·m–3 to 10.4–16.2 mg·m–3. CPUE increased from 2.1–5.5 kg·h–1 to 5.8–14.5 kg·h–1. The species number of fish, crustaceans, cephalopods and shellfish increased 25, 3, 2 and 3, respectively. The Shannon-Wiener biodiversity index of fish, crustaceans, cephalopods and shellfish increased 0.5, 0.4, 0.1 and 1.0, respectively. Both biomass and density of zoobenthos also increased. The construction of marine ranching in Zhelin Bay has restored the habitat to some extent, and played positive role in the conservation and proliferation of fishery resources.
Latest Accepted  doi: 10.12131/20180119
[Abstract](106)
Abstract:
The gential system of female Harpiosquilla harpax consists of ovary, fallopian tubes and thelycum. We collected a total of 168 female H. harpax and dissected individually for comparison of the developmental features of thelycum and ovary from different individual, and ultramicroscopic observation of contents in the milky-white thelycum. The results show that the females had paired ovaries that lied between the dorsal heart and the ventral digestive glands and gut, which originated posteriorly carapace to telson. The apparent color of ovary was changeable as follows: colorless-rayish yellow-earthy yellow-light yellow-orange, and the matured ovaries were orange or pink. The gonadosomatic index (GSI) were 1.62±0.53, 2.73±0.44, 3.82±0.48, 6.84±1.04 and 11.63±2.11, respectively. The females had three parallel strips that were visible through the exoskeleton on the sixth, seventh, and eighth thoracic sternites, which were organ for sperm-storage, and the apparent colours of thelycum were changeable as colorless and transparent-light white and turbidity-milk white and dense. The more matured ovary was, the heavier milk white of thelycum became. Group of sperms with membranes had been observed in the thelycum contents which were filled with filamentous stroma. The shape of sperm was spherical but without flagellum and acrosome, size of 1~3 μm. The results provide references for further research on the reproductive biology and artificial breeding of H. harpax.
Latest Accepted  doi: 10.12131/20180099
[Abstract](115)
Abstract:
In order to achieve high-value utilization of abandoned Porphyra haitanensis, we studied the enzymatic hydrolysis technique and antioxidant activity of P. haitanensis protein. Single factor test and response surface optimization test were used to screen the optimum protease and enzymolysis parameters based on the indices of hydrolysis degree and reducing power. The antioxidant activity of the hydrolysate was studied by determining the reducing power of hydrolysate and scavenging ability of hydrolysate on the free radicals DPPH, ·OH and O2·. The results show that neutral protease was the optimal enzyme among the six enzymes. The optimum conditions for the hydrolysis of P. haitanensis proteins were as follows: substrate concentration 35 g·L–1, enzyme dosage 31200 U·g–1, hydrolysis temperature 45 ℃, pH 7.6, hydrolysis time 5 h. Under these conditions, the hydrolysis degree was 31.37% and the reductive power was 2.2. The scavenging rates for DPPH, ·OH and O2·were 56.26%, 85.84% and 72.74%, respectively, which indicates that P. haitanensis can be hydrolyzed by neutral protease effectively, and its hydrolysate has good antioxidant activity and application prospects.