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Available online   , doi: 10.7541/2019.009
[Abstract](193) [FullText HTML](67) [PDF 529KB](62)
Abstract:
This study was conducted to investigate the effects of 4 kinds [24L﹕0D (D1), 16L﹕8D (D2), 8L﹕16D (D3), 0L﹕24D (D4)] of photoperiods on feed consumption, digestive enzyme activities and blood hormone of turbotScophthalmus maximus L. juveniles with initial body weight of (30.5±2.0) g in 20 hours (8:00am—4:00am). The results showed that the feed rate decreased with the shorten of illumination time, and feeding peak in D1 group appeared every 8h, meanwhile others appeared at 8:00am and 4:00pm. Activities of protease and amylase of former 3 groups were appeared spike at 12:00am and 8:00pm, and lipase was significantly higher than that of the D4 group. There were no difference of GH contents from 8:00am to 8:00pm among all groups, and D1 group at 4:00am was significantly higher than others, but D4 group was significantly lower than others from 0:00am to 4:00am. COS contents of D1, D2 and D3 groups were not significant difference in 8h after first feeding, and then increased firstly and decreased afterwards; D4 group reached the maximum level at 8:00pm. NE content of D1 and D2 groups were significantly higher than that of the others at 0:00am, meanwhile D4 group was significantly lower than others at 8:00pm. T3 content of D2 group was significantly higher than that of the other groups at 8:00am and 12:00am; D4 group was lower at 8:00pm, and higher at 0:00am than others; D2 and D3 group were lower than those of D1 and D4 group at 4:00am; The highest values of T3 of all groups were appeared at 8:00pm. These results demonstrated that feed intake, digestive enzyme activities and serum hormone contents of turbot juvenile were affected by photoperiod under current experimental conditions. 8—16 lighting period and feed twice daily would be recommended for turbot culture under this intensity of illumination.
Available online   , doi: 10.7541/2019.027
[Abstract](117) [FullText HTML](33) [PDF 665KB](25)
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We discovered for the first time that Grateloupia turuturu filaments, which developed from discoid crusts, had the ability to form spores under laboratory condition. We hereby defined this category of spores as" disc-filamentospore”. The formation of disc-filamentospores were observed and the effect of various temperatures (6, 12, 16, 20, 24, 30℃) and light intensities (10, 30, 45, 60, 90, 120 μmol/(m2.s)) on the release of disc-filamentospores were analysed. The results indicated that: (1) Carpospores, which formed and released from cystocarps of female gametophyte of G. turuturu, first developed into discoid crusts. Then the discoid crusts were induced to form filaments of monolayer cells, which formed massive plurilocular sporangiums and released large amounts of disc-filamentospores. (2) The formation and release were significantly affected by temperature and light intensity. Our study revealed that the releasing efficiency of disc-filamentospores could get the maximum at 16℃ and 6 0 μmol/(m2·s). (3) The releasing number of disc-filamentospores was evidently reduced when the temperature was lower than 12℃ or higher than 24℃. (4) When the light intensity was less than 30 μmol/(m2·s) or more than 90 μmol/(m2·s), the releasing efficiency of disc-filamentospores was inhibited significantly. Our results improved the asexual reproduction process of Grateloupia turuturu and provided more abundant theoretical basis for its germplasm preservation, artificial breeding and aquaculture. Finally, we suggest a plausible solution to investigate the origin and evolution of Grateloupia turuturu.
Available online   , doi: 10.7541/2019.028
[Abstract](150) [FullText HTML](48) [PDF 465KB](50)
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Growth rate, feeding, development of organs, disease resistance, adaptability, and self-regulation to the change of environment are all associated with fish health assessment. With the rapid development of aquaculture, the assessment of fish health condition is increasingly important. The present manuscript reviewed the evaluation procedures and indices related to fish health condition and available shortcomings, and also discussed the possibility of developing new methods to assess fish health condition using computer technology and biotechnology, which are expected to provide new insights for fish health assessment.
Available online   , doi: 10.7541/2019.026
[Abstract](104) [FullText HTML](32) [PDF 630KB](17)
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Microcystis bloom has caused many environmental problems, and its mechanism of bloom-formation and adaptation has been noticed wildly. To examine the possible information transfer by chemicals between both algae, the effect of Ochromonas and its culture media filtrate on the growth and physiological traits of Microcystis aeruginosa was investigated in this study. The results indicated that the cell density in Microcystis decreased significantly, while the cell density in Ochromonas increased markedly when Microcystis and Ochromonas were co-cultured at three initial cell density (1﹕4, 1﹕1 and 4﹕1). Moreover, the culture media filtrate ofOchromonas sp. could inhibit the growth, and resulted in an increase of malondialdehyde (MDA) content and catalase (CAT) activity. Additionally, the content of extracellular polysaccharides (EPS) increased markedly in Microcystis when it was inoculated into the culture media filtrate of Ochromonas sp. These results indicated that Ochromonas not only could prey on Microcystis, but also might release some of the chemicals to inhibit the growth and physiological parameters of Microcystis. This suggested that Ochromonas might be used to inhibit the early proliferation of algae as a potential control of algae blooms.
Available online   , doi: 10.7541/2019.001
[Abstract](110) [FullText HTML](27) [PDF 784KB](18)
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Through regulating the post-transcriptional maturation of UsnRNAs (U-rich small nuclear RNAs), integrator complex has an effect on the intron splicing of pre-mRNA. Therefore, integrator complex plays an important role in the production of mature mRNA. However, the regulation and developmental functions of integrator complex are poorly understood in vertebrates. In this study, zebrafish (Danio rerio) was used to generate the ints12 knockout model by CRISPR/Cas9, and two homozygous lines were generated with different frame-shifts. Observation on the misprocessing of UsnRNA 3′ ends in zygotic mutant of ints12 (Zints12) was conducted through real-time quantitative PCR analysis. When compared with the control fish, the overall growth of Zints12 was largely retarded, and the Zints12 population was all-male. Further studies showed that cell proliferation was significantly interfered, and the level of introns retention of ints12 transcripts was significantly increased in Zints12, suggesting an " auto-regulation loop” in the splicing regulation by ints12. Overall, we obtained homozygous mutants of zebrafish ints12 by gene knockout technology and revealed that zebrafish ints12 regulates UsnRNA 3′-box processing to exert various effects on early embryonic development and body growth.
Available online   , doi: 10.7541/2019.002
[Abstract](93) [FullText HTML](33) [PDF 699KB](21)
Abstract:
In order to investigate the role of TRAF6 in Lethenteron morii with signal pathway of TLR, the full-length cDNA of LmTRAF6 was cloned. The distribution of tissues (supraneural body, gill, intestine, kidney) and related gene expression in both juvenile and adult were studied with real-time quantitative PCR. Additionally, the change of gene expression in those tissues from adult L. morii was also examined after challenged by Pseudomonas aeruginosa. A recombinant plasmid pEGFP-TRAF6 was constructed by the double digestion method, and transformed into the HEK293T cells. Fluorescence observation was conducted after 48 hours, and the results were photographed. The results showed that the length of LmTRAF6 cDNA was 2751 bp, including 1785 bp open reading frame (ORF) and 594 amino acids. The structure of LmTRAF6 was highly similar to that in other mammal and fish species, containing one RING domain, one coiled-coil region, one MATH domain and two zinc fingers. Phylogenetic tree showed that LmTRAF6 was evolutionarily closer to that in mammals and fishes, but not to that in Drosophila melanogaster and Penaeus chinensis. LmTRAF6 was expressed in all tested tissues and their developmental stages. However, higher expression was detected in heart, skin, gill, liver of juvenile, as well as in kidney, gill, and muscle of adult. When adult L. morii was challenged by Pseudomonas aeruginosa, the expression of LmTRAF6 in gill, intestine and kidney reached to the peak after 24h. Subcellular localization showed that LmTRAF6 was expressed in both cytoplasm and nucleus.
Available online   , doi: 10.7541/2019.014
[Abstract](185) [FullText HTML](89) [PDF 725KB](26)
Abstract:
The grass carp (Ctenopharyngodon idellus) infected with the hemorrhage virus was used to analyze the intestinal microbiota by using high-throughput sequencing. The results showed that microbiota significantly differed between grass carp reovirus (GCRV)-infected and control grass carp (multiple response permutation procedure (MRPP), analysis of similarity (ANOSIM), and Adonis; P<0.01). When we compared alpha diversity, we found that Shannon-Wiener index, inverse of Simpson's original index and Pielou’s evenness index of intestinal microbiota were all significantly decreased after infecting with GCRV (independent samplest-test, P<0.05). Besides, we found that the individual difference within GCRV-infected group was significantly greater than that in the controls (Wilcoxon signed-rank test,P<0.05), suggesting that the intestinal microbiota in GCRV-infected grass carps became disorganized and lost their original balance. Proteobacteria, Firmicutes, Fusobacteriaceae, and Bacteroidetes were dominant phylum in both GCRV-infected group and controls. However, the relative abundance of operational taxonomic units (OTUs) between the two groups was different. For example, OTU_69 (Pasteurellaceae), OTU_504 (Comamonadaceae), and OTU_1898 (Cetobacterium) were all significantly lower than that of controls (t-test, P<0.05), confirming that GCRV could make intestinal microbiota of grass carps became disorganized. The stability of intestinal microbiota is important for health of host. By detecting changes in the intestinal microbiota of GCRV-infected grass carp, we will be able to provide theoretical basis and data reference for the prevention and treatment of common disease of farmed fish, as well as providing a reference for healthy breeding.
Available online   , doi: 10.7541/2019.021
[Abstract](143) [FullText HTML](86) [PDF 708KB](15)
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In this study, the method of irradiation breeding was applied to wetland plants in order to improve its cold resistance. Herein, 25, 45, 60 and 80 Gy doses of gamma ray were used to irradiate Canna indica Linn (CIL) seeds, and the dose rate was 6 Gy/min. After CIL seeds were grown up, they were exposed to a low temperature stage, and their cold hardiness was accordingly evaluated. The results showed that the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in irradiated CIL seeds were higher than that of the control group. Malondialdehyde (MDA) in control group accumulated in large quantities under low temperature, which was higher than that of the irradiation treatment group. Besides, at low temperature, the content of proline, the total soluble sugar, and protein of irradiated seedlings were totally higher than that of the control group. The score of cold resistance in irradiated group was also higher than that of the control group, and the 45 Gy dose of gamma ray group showed the highest score. Moreover, CIL with the strongest cold resistance was planted in the constructed wetland to evaluate its purification effect in winter, and evaluation indexes were total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD). Results revealed that the removal rate of TP in the group of CIL in constructed wetland by using 45 Gy dose of gamma ray was significantly higher than that of the control group (P<0.05). It can be concluded that irradiation treatment can effectively improve the cold resistance ofCIL and enhance the effect of artificial wetland purification in winter.
Available online   , doi: 10.7541/2019.024
[Abstract](65) [FullText HTML](40) [PDF 733KB](5)
Abstract:
A newly isolated spontaneously flocculating microalgae Parachlorella kessleri F01 was used as the material, and the algae sample in autotrophic cultivation of one-step culture method was used as the control group. A two-step culture method was designed in which glucose was supplemented for mixotrophic cultivation at stage Ⅰ, and nutritional limitation treatments were done at stage Ⅱ, and we studied their effects on the lipid accumulation and flocculation performance of the algae. The algae cell number was determined by a hemocytometer. Biomass was measured via dry weight, and the total lipid was quantified with staining method. The extracellular polymeric substances (EPS) components of algae were analyzed by three-dimensional fluorescence spectroscopy. The results showed that: (1) The optimum glucose concentration was 10 g/L at stage Ⅰ. The alga lipid productivity reached to 204.25 mg/L/d on the 10th harvesting day, which was 16.20 times of that in the control group, and the self-flocculation rate of alga cell was 96.1% after sitting for 12h, which has no significant difference with that in the control group. (2) On the basis of stage Ⅰ, alga cells were cultured for 1 day in stage Ⅱ with different elemental treatments. The alga lipid productivity were 242.64 mg/L/d and 227.61 mg/L/d in the low-glucose group and the low-glucose coupled with low-nitrogen group, respectively, increasing by 18.8% and 11.4% of those at stage Ⅰ. After 4 days cultivation, the alga lipid productions of the four treatment groups including low-glucose, no-glucose, low-nitrogen and the low-glucose coupled with low-nitrogen significantly increased compared with those in the control group and stage Ⅰ. The highest production reached to 3.08 g/L in the low-glucose and low-nitrogen co-treatment group, which was 23.69 times of that in the control group, and increased by 51.0% compared with that in stage Ⅰ. The self-flocculation rates in four treatment groups at stage Ⅱ were nearly above 85.0%, which could satisfy the harvesting requirements. (3) The content of protein tryptophan in alga EPS was positively related to the self-flocculation rate. Different culture treatments could change the protein tryptophan content in EPS of algae cells, and thus affect their flocculation performance. Self-flocculation Parachlorella kessleri F01 is an excellent potential alga for biodiesel production. The two-step culture method can greatly enhance its lipid production. The advantage of self-flocculation combined with two-step culture method is expected to be the key breakthrough to solve the bottleneck of biodiesel production technology of microalgae.
Available online   , doi: 10.7541/2019.011
[Abstract](139) [FullText HTML](72) [PDF 447KB](34)
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This study was conducted to investigate the effect of transportation stress on the plasma biochemical indices, body color, fish quality of gibel carp [Carassis auratus gibelio var. CAS III, body weight of (116.46±2.09) g] and also water quality. Transportation was simulated on an automobile vibration bench for 4h. After 4h simulative transportation, the ammonia concentration of water in bags increased significantly (P<0.01), and the dissolved oxygen of water in bags was increased (P<0.05), while the pH value decreased significantly (P<0.05). Fish plasma cortisol, glucose and MDA concentration increased significantly (P<0.01), while plasma lactic acid concentration decreased (P<0.01). Plasma GSH-PX significantly decreased after 4h simulative transportation (P<0.05), and plasma SOD and CAT had a low value after simulative transportation (P>0.05). Dorsal skin showed significantly decreasing L* values after 4h simulative transportation (P<0.01), and the abdomen and lateral line L* values also decreased with no significance (P>0.05). While a* (P>0.05) and b*(P<0.05) values declined in these three parts after 4h transportation. Cohesiveness, chewiness and resilience decreased significantly in fillet (P<0.05). The fillet gumminess, springiness and adhesiveness were slightly decreased (P>0.05), while its hardness increased (P>0.05). The results indicated that transportation could induce stress response of gibel carp and reduce fish quality.
Available online   , doi: 10.7541/2019.023
[Abstract](47) [FullText HTML](24) [PDF 745KB](5)
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There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton, and elevated atmospheric CO2 concentration can affect the photosynthetic capacity of marine diatom to different degrees, however, little attention had been paid to their interaction on diatom. In this study, the growth rate, net photosynthetic (Pn) rate, biochemical composition, extracellular carbonic anhydrase (eCA) activity, and Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activity were investigated when Phaeodactylum tricornutum was grown under different light intensities and CO2 concentrations. The results showed that the specific growth and Pn rates in P. tricornutum were not significantly affected by CO2 concentration under low light intensity, whereas in presence of the high light intensity (HLI), elevated CO2 concentration was beneficial to promote the increase of the rate of Pn. The eCA activity, chlorophyll content, and soluble protein content decreased with increase of CO2 concentration, regardless of the high or low light. It was revealed that no significant difference (P=0.6) was found in the net photosynthetic (oxygen evolution) rate between the high-CO2 (HC)- and low-CO2 (LC)-grown plants. Under LLI, RuBisCO activity of HC-grown algae was 2.42 and 1.39 times higher than that of LC- or MC-grown ones. However, RuBisCO activity of HC-grown algae was 6.72 and 3.45 times greater than that of LC- or MC-grown ones under high light. These results indicate that the algae can adapt changes of light intensity and CO2 concentrations in the environment by adjusting the allocation of energy during the operation of the CO2-concentrating mechanism and photosynthesis.
Available online   , doi: 10.7541/2019.020
[Abstract](82) [FullText HTML](31) [PDF 680KB](14)
Abstract:
In order to understand the community characteristics of zooplankton and relationships with environmental factors, and aimed to use zooplankton community parameters monitoring the water quality of water source reservoirs, a seasonal investigation was conducted on the water quality parameters, abundance and biomass of zooplankton in water source reservoirs (K1— K10) from January, 2014 to October, 2016 in Zhejiang Province. The relationships and action mechanism between water environment factors and zooplankton abundance and biomass were studied by the method of multiple stepwise regression and path analysis. The results showed that the average abundance of zooplankton in the reservoirs was 97.5 ind./L from 2014 to 2016, mainly composed of copepods nauplii (36.3%), Rotifer (28.4%) and Cyclops (20.0%). The average biomass was 289.3 μg/L, which was mainly composed of Cladocera (39.3%), Cyclops (29.0%) and Cyclops (14.5%). Chl. a content was the decisive factor of zooplankton abundance in spring and summer, and TP content was the limiting factor for fluctuation of community abundance in autumn and winter, and the community abundance was affected by TN through N﹕P ratio in spring. DO content was a decisive factor in the development of zooplankton biomass in winter and summer, and the community biomass was promoted by DO through reducing N﹕P ratio in winter. The present zooplankton stock in the reservoirs was affected by the fluctuation of TP content, the change of N﹕P ratio and the Chl.a content of the water body ultimately reflected.
Available online   , doi: 10.7541/2019.019
[Abstract](223) [FullText HTML](131) [PDF 685KB](32)
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In order to provide basic information for protecting and rational utilizing resources of the Yangtze Estuary, feeding types, trophic level, energy flow, and food web, 43 aquatic animals were studied by using stomach content analysis. The species were classified into four groups according to their feeding habit: plankton feeding, benthic feeding, nekton feeding, and mixed feeding (benthic and nekton feeding). Among the samples collected in this study, the plankton predators were dominant accountings for 39.53%, and the nekton predators had the minimum dominancy, accounting for 11.63%. The results of trophic level showed that according to the dietary habits, these aquatic animals can be also divided into 3 different groups, which herbivorous consumers were dominant, and accounted for 76.75%, while intermediate carnivorous fish had the minimum dominancy, accounting for 4.65%. Through the overfishing and environmental degradation, the trophic levels of the 12 common fish in the Yangtze Estuar were generally lower than those of the 1990s, the average trophic level dropped from 3.80 to 2.87. According to each consumer’s stomach content, this study determined the benthic algae and phytoplankton, and organic detritus, including particulate organic matter (POM), as the main producers of the Yangtze Estuar aquatic food web, and drew their own energy flow. Eventually, based on the nutritional relationship among different aquatic animals, this study proposed a simplified model for the Yangtze Estuar aquatic animals’ food web.
Available online   , doi: 10.7541/2019.013
[Abstract](70) [FullText HTML](29) [PDF 942KB](8)
Abstract:
To investigate the effects of acute cold stress on the mucosal histology in different sections of the juvenile Pelodiscus sinensis, the activity of serum diamine oxidase (DAO) and histological features of intestinal mucosa in Chinese soft-shelled turtle in culture temperature and acute cold stress were conducted. The first acute cold stress reduced the DAO activity with the lowest level at 48 h after cold stress. In the acute cold stress and rewarming experiment, the DAO activity decreased significantly after 3 days of cold stress and then restored to normal level with the recovery of temperature. Histopathological results showed no significant difference in the morphology of mucosal epithelium in the intestine (posterior segment of ileum and large intestine) between acute cold stress group and control group. There were no significant difference in the number of goblet cells, the length of villus and the ratio of villus length to crypt depth in the posterior segment of ileum between acute cold stress group and control group, while the mucosal thickness in the posterior segment of ileum significantly decreased in the acute cold stress group in comparison to control group. Acute cold stress significantly reduced the large intestine number of goblet cells. The structures of the intestinal mucosal mechanical barrier of Chinese soft-shelled turtle under acute cold stress are an intestinal segment dependent pattern. These results suggest that the various segments of the intestine of Chinese soft-shelled turtle have a special response style to acute cold stress.
Available online   , doi: 10.7541/2019.004
[Abstract](73) [FullText HTML](30) [PDF 1172KB](9)
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In this study, the cDNA sequences of FcγRα and FcRγ subunits of FcγR rainbow trout were cloned for the first time by RACE technique. The sequences of FcγRα and FcRγ were analyzed by using bioinformatics software. The expressions of the genes in different cell subpopulations and tissues, as well as in the head kidney after Poly (I∶C) and lipopolysaccharide (LPS) stimulations were analyzed by real-time fluorescent quantitative polymerase chain reaction (PCR). The results showed that the full-length cDNA of FcγRα is 1677 bp with an open reading frame (ORF) of 954bp encoding 317 amino acids. The FcγRα is composed of a signal peptide and two Ig-like domains, however, without including transmembrane and intracellular regions. There are three kinds of FcγR subunit, involving FcRγ1, FcRγ2a, and FcRγ2b. FcRγ1 and FcRγ2 genes are located on different chromosomes, while FcRγ2a and FcRγ2b are two splicing isoforms of FcRγ2 gene. These subunits are composed of signal peptide, transmembrane domain, and immunoreceptor tyrosine-based activation motif (ITAM). Amino acid sequence similarity analysis showed that the highest identity (30%) of FcγRα is between rainbow trout and channel catfish (Ictalurus punctatus), and FcRγ1 and FcRγ2a/2b in rainbow trout have the maximum sequence identity (40%) with mammalian FcRγ. Tissue distribution analysis showed that the expression of FcγRα, FcRγ1, and FcRγ2a/2b was higher in head kidney, spleen, and blood cells, respectively. Analysis of cell subpopulations showed that the expression of FcγRα, FcRγ1, and FcRγ2a/2b was the highest in the myeloid cell population. In addition, the expression of FcγRα, FcRγ1, and FcRγ2a/2b in the head kidney was significantly up-regulated after LPS and Poly (I 鲶C) stimulations, indicating that FcγR plays an important role in the antibacterial and antiviral immunity.
Available online   , doi: 10.7541/2019.025
[Abstract](132) [FullText HTML](79) [PDF 944KB](14)
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In this study, we explored the ability to remove nitrate and phosphorus of two strains of Stigeoclonium spp. (SHY-370 and HB1617) by setting different initial concentrations of ammonia nitrogen and nitrogen/ phosphorus (N/P) ratios in synthetic wastewater. The results indicated that different initial concentrations of ammonia nitrogen in synthetic wastewater could affect the biomass concentration and the ability to remove N and P of SHY-370 and HB1617. The maximum ammonia nitrogen concentration in synthetic wastewater that SHY-370 can tolerate was 10mg/L, while that was 5mg/L for HB1617. The ammonia-nitrogen removal rate of SHY-370 and HB1617 was above 97% and the maximum daily ammonia-nitrogen removal rate was 3.98 mg/L/d, while the initial concentration of ammonia nitrogen in synthetic wastewater varied between 1-10mg/L. N/P ratios had a slight impact on the biomass concentration of the SHY-370, however, the biomass concentration of HB1617 was reduced when the corresponding rate was over 20 mg/L. The concentration of total phosphorus (TP) in synthetic wastewater was 10mg/L. When the N/P ratio was 2, the content of TP in synthetic wastewater was higher than 10mg/L, which led to a low TP removal rate. According to the results of our study, we can conclude that SHY-370 and HB1617 are appropriate for the treatment of urban sewage in which the concentration of ammonia nitrogen is relatively low, whereas the concentration of TP and NO3-N is relatively high.
Available online   , doi: 10.7541/2019.022
[Abstract](49) [FullText HTML](32) [PDF 787KB](4)
Abstract:
To explore the cause of Potamogeton lucens’s decline, a dominant plant inhabiting the shallow water of Nansi Lake, the physiological and biochemical changes of P.lucens were examined under a group of constant temperatures at 25℃, 30℃, 35℃, and 40℃, respectively, for 3h. The results showed that the contents of protein, soluble sugar and chlorophyll decreased significantly, while the content of malondialdehyde (MDA) increased significantly at a high temperature above 35℃. The results indicated that high temperature above 35℃ had significant damage to P.lucens. The photosystem of P.lucens was more sensitive to heat stress. The characteristics of standardized chlorophyll fluorescence kinetics curves under heat stress were as follows. Peaks at J and K phases were observed, but no L-band was found on the normalized chlorophyll fluorescence kinetics curves. The chlorophyll fluorescence parameters were calculated from the OJIP curves of the heat-treated leaves. The results showed that the initial closing speed of the reaction center (dVG/dto, dV/dto) slowed down with the increase of temperature under heat stress, but it took a shorter time to reach the maximal fluorescence (Tfm). The maximum quantum yield of PSII (Photosystem II) photochemistry (Fv/Fm) decreased. However, the non-photochemical constants (Kn), relative variable fluorescence at the J-step (Vj), and dissipated energy flux (DIo/RC, DIo/CSo, Fo/Fm) increased under heat stress. Although the turn-over number of QA (N), average redox state of QA (Sm/Tfm), and relative variable fluorescence at the I-step (Vi) barely changed, the plastoquinone pool (Sm) decreased significantly at high temperature. Absorption and trapped energy flux per RC (ABS/RC, TRo/RC; reaction center, RC) increased, whereas the electron transport efficiency per RC (ETo/RC) decreased when temperature increased. Heat stress also decreased the trapped energy flux, electron transport flux and density of RCs per CS (TRo/CSo, ETo/CSo, RC/CSo; cross section, CS). These effects of heat stress on photosystem eventually led to a significant reduction in the structure and function index (SFIabs), performance index (PIabs), and drive force for photosynthesis (DF) of the P.lucens leaves. These results demonstrated that heat stress mainly caused inactivation of oxygen-evolving complex of PSII, reduction of the density of RCs, and decrease of photochemical efficiency of RC in P.lucens plants, and these led to the production of reactive oxygen species, and thus caused remarkable damage to cells. Therefore, P.lucens is a sensitive aquatic plant to high temperature in summer.
Available online   , doi: 10.7541/2019.018
[Abstract](62) [FullText HTML](23) [PDF 973KB](15)
Abstract:
Hukou section, the connection between the Yangtze River and Poyang Lake for the migration route of many fish species, plays a vital role in the proliferation of fish. A systematic investigation on larval and juvenile fish resources were conducted during the fish breeding period in the Hukou section from May to August 2016. The community structure, dominant species, fish density, time-space distribution and their relationships with environmental factors in Hukou section were studied during the continuous 88-day investigation. A total of 39 larvae and juvenile taxonomic groups including 7 orders and 12 families were identified. Among them, 37 were identified to species level, one was identified to subfamily, and one was identified to family. Hemiculter bleekeri is the first dominant species and other dominant species are Gobiidae, Parabramis pekinensis, Pseudolaubuca sinensis. The larval and juvenile fish density reached its peak level on July 1 with 1230.77 ind./100 m3. The overall fish density showed a trend of decreasing volatility from July 1 to August 15. The cluster analysis divided 6 periods into 2 groups: Late May to early July in group Ⅰand late July to early August in group Ⅱ. Hemiculter bleekeri, Culter alburnus, Coilia nasus, etc. peaked in late June and Parabramis pekinensis, four famous domestic fishes, Siniperca chuatsi, etc. peaked in early July. The density of larval and juvenile fish on the south and north sides of the section were higher than that of the center section. Redundancy analysis (RDA) found that water temperature, transparency, and flow are the main environmental factors affecting the community structure of larval and juvenile fish. Correlation analysis showed highly significant correlation between water level and larval and juvenile fish density (P<0.01). This study indicates a large amount of fishes of early life history in Hukou section. The community structure of larval and juvenile fish is dominated by middle and small-sized fishes, and the proportion of river-lake migratory fishes are relatively high. Larval and juvenile fish have different adaptation characteristics to various environmental conditions. The species showed different degrees of positive and negative correlations with water temperature, transparency and flow. The results provide the scientific basis for the protection strategy of fisheries resource in the middle-lower reaches of the Yangtze River.
Available online   , doi: 10.7541/2019.16
[Abstract](53) [FullText HTML](27) [PDF 802KB](8)
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Different species of Rhodeinae have been wildly distributed across China. Different species have shown very similar morphological characteristics, making their distinguish to be indeed difficult. In order to compare the morphological differences among Rhodeus sinensis, Acheilongnathus tonkinensis, A. macropterus, A. chankaensis and A. taenianalis by the morphometric characteristics, and enrich the classification features, multivariate morphometrics were used to analyze the morphological variations of five Rhodeinae species in Huaihe River Basin (Henan province, China). The results showed that there were significant differences in the body’s width/body’s length, head’s length/body’s length, snout’s length/body’s length, caudal peduncle’s length/body’s length, dorsal fin base’s length/body’s length, pectoral fin’s length/body’s length, pelvic fin’s length/body’s length, and head’s length/snout’s length among the five species (P<0.01), and there were significant differences in the total length/body’s length and body’s height/body’s length (P<0.05). Therefore, these differences mainly focus on the head, tail, fin, and so on. Principal component analysis, discriminant analysis, and cluster analysis showed that the five species had obvious morphological differences, the most significant difference betweenA. taenianalis and A. tonkinensis was found, and the most insignificant difference was observed between A. taenianalis and A. macropterus. The discriminant accuracy rate of the five species varied from 82.35% to 100%, effectively realizing the distinguish of the five Rhodeinae species.
Available online   , doi: 10.7541/2019.017
[Abstract](49) [FullText HTML](21) [PDF 793KB](4)
Abstract:
To establish a simple and reliable index for determining silvering stages of the Japanese eel, Anguilla japonica, we observed the colorations of various body parts and biological characteristics on the reproductive stock of theeels collected in the Yangtze River estuary before starting their oceanic migrations. The characteristics of body color, and the changes in age, total length, body weight, and silvering index were analyzed in the silvering process of the Japanese eel. The two silvering stages are characterized by the colorations of trunk skin as follows: (1) Pre-silver stage: pigments deposited completely on the upper edge of pectoral fin on the lateral sides of trunk, (2) Silver stage: pigments deposited completely on the lower edge of pectoral fin on the lateral sides of trunk.Our results indicated that body size, eye diameter, pectoral fins length and gonad-somatic indexincreased from pre-silver stage to silver stage during the ontogenic process of silvering, and digestive tract index decreased in contrast. The principal component analysis suggested thatthe silver stage eels had enlargement of the eye and pectoralfins, high sexual maturity and the degenerated disgestive tract compared to pre-silver stage eels. Because Japanese eel must swim three thousands kilometers from the growth habitats in northeast Asia to reach the West Mariana Ridge spawning area without feeding, these various modifications to the bodies and physiological changes had indicated that silver eels develop various adaptations that prepare them for their long oceanic migrations. The silver stage eels and pre-silver stage eels could be also distinguished by canonical discriminant function analysis using five characters, which showed up 95% reliability of their correct classification. Our results also suggested that an eye index of about 5.0 is a cut off point for distinguishing the silver stage from the pre-silver stage of the Japanese eels for a convenient use of field survey.
Available online   , doi: 10.7541/2019.015
[Abstract](73) [FullText HTML](27) [PDF 557KB](16)
Abstract:
To investigate the structure characteristics of skeleton of Acipenser baeri, the conventional method was used to study the skeletal system of A. baeri Brandt mainly focusing on morphology and taxonomy. The results showed that the skeletal system ofA. baeri Brandt juvenile consists of two parts, axial skeleton and appendicular skeleton. The axial skeleton of A. baeri was composed of skull, vertebral column and ribs. The appendicular skeleton of A. baeri included fin-ray, pterygiophore and girdle. We found that the skeletal system ofA. baeri Brandt was more similar to Acipenser schrencki Brandt than other sturgeons, which probably explained by the long-term life adaptation to the high latitude and low temperature environment.
Available online   , doi: 10.7541/2019.012
[Abstract](104) [FullText HTML](65) [PDF 753KB](12)
Abstract:
To investigate the effects of histamine and Lactobacillus reuteri on Pelteobagrus fulvidraco, three isonitrogenous diets, namely diet C (control, with a 147 mg/kg content of histamine), diet H (with a 479 mg/kg content of histamine) and diet H+B (histamine+ bacteria: a 496 mg/kg content of histamine and 1×105 CFU/g L. reuteri), were formulated for a 56-day trial of P. fulvidraco juveniles (14.23±0.65) g. Our data indicated that plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity were significantly lower in group H+B compared with those of group H (P<0.05), while there was no significant difference between group H+B and group C (P>0.05). Meanwhile, liver glutathione-s-transferase (GSH-ST) activity and malondialdehyde (MDA) content were dramatically reduced in group H+B compared with those of group H (P<0.05), while there was no significant difference between group H+B and group C (P>0.05). Furthermore, the HE staining showed that there were inflammatory cells infiltrating in the liver of fish fed with diet H, while no hepatocyte abnormality observed in group C and group H+B, and that the intestinal folds decreased significantly with shorter and edema in diet H group, while this is no marked difference in the length of intestinal folds between group C and H+B. Overall, our studies indicated the protective effect ofL. reuteri against histamine in cultured fish diet.
Available online   , doi: 10.7541/2019.010
[Abstract](180) [FullText HTML](114) [PDF 530KB](13)
Abstract:
To investigate the effects of exhaustive chasing training on parameters of respiratory and circulatory system and excess post-exercise oxygen consumption (EPOC) in juvenile qingbo (Spinibarbus sinensis) and rock carp (Procypris rabaudi), sixty samples of S. sinensis (28.36±0.08) g and sixty samples of P. rabaudi (19.53±0.13) g were randomly divided (equally 30 fish in each group) into control group and training group, respectively. Then, these fish in the training group were analyzed under exhaustive chasing training once per day for 3 weeks at 25℃ to measure the heart index, gill index, hematological parameters, and EPOC. The results showed that there were no significant differences in the heart index, gill index, hemoglobin content, and number of red cells between the control group and training group of S. sinensis and Procypris rabaudi(P<0.05). The gill index in the control group ofP. rabaudi was significantly lower than that in the control group of S. sinensis(P>0.05), whereas the heart index, hemoglobin content, and number of red cells in the control group ofP. rabaudi were not significantly different than that in the control group of S. sinensis(P<0.05). No significant differences were found in pre-exercise metabolic rate, peak post-exercise metabolic rate, factorial metabolic scope, and recovery rate between the control group and training group (P>0.05), whereas duration of EPOC in the training group was significantly higher than that in the control group ofS. sinensis (P<0.05). The pre-exercise metabolic rate in the control group was significantly lower than that in the training group (P<0.05), whereas peak post-exercise metabolic rate and factorial metabolic scope, duration of EPOC, and recovery rate in the control group were not significantly different than that in the training group ofP. rabaudi(P>0.05). The pre-exercise metabolic rate, peak post-exercise metabolic rate, EPOC magnitude, and recovery rate in the control group ofP. rabaudi were significantly lower than that in the control group of S. sinensis(P<0.05), whereas factorial metabolic scope and duration of EPOC in the control group ofP. rabaudi were not significantly different than that in the control group of S. sinensis(P>0.05). Our results suggested that (1) exhaustive chasing training had no significant effects on the parameters of respiratory and circulatory system ofS. sinensisandP. rabaudi(P>0.05); (2) exhaustive chasing training significantly increased anaerobic capacity ofS. sinensis(P<0.05); and (3) the pre-exercise metabolic rate and peak post-exercise metabolic rate ofS. sinensis were significantly higher than those of P. rabaudi(P<0.05), which may be related to active habits ofS. sinensis.
Available online   , doi: 10.7541/2019.003
[Abstract](57) [FullText HTML](20) [PDF 703KB](7)
Abstract:
The next-generation sequencing technology was used to obtain the whole mitochondrial genome sequences of Gadus macrocephalus. The mitochondrial gene was annotated and its structure was analyzed. The results showed that the circular genome was 16569 bp in length with typical mtDNA components. The mitochondrial genome encodes 13 proteins and 22 tRNAs, 2 rRNAs and a D-Loop region. The base composition showed a tendency of high AT and AT weak negative skewness. There were five kinds of termination codon in the protein coding gene of G. macrocephalus mitochondria, including AGG and AGA which were commonly found in mammalian mitochondria. It was shown that most of the tRNA structures share the classical clover shape, but the tRNA-Ser(GCT) is unique because of a shortage of DHU. Two sequences with the functions of TAS and CSB, as well as 17 bp pyrimidine-rich sequences were found in D-Loop region. The non-coding region contains a conserved sequence controlling the initiation of light chain replication (OL) and a gene spacer with 74 bp. Based on the whole mitochondrial genome sequence and the Cytb gene, the phylogenetic trees were constructed separately with several cod fish that belong to Gadiformes. The results provide an important evidence to reveal the evolutionary status of the pacific cod.
Available online   , doi: 10.7541/2019.008
[Abstract](53) [FullText HTML](28) [PDF 442KB](9)
Abstract:
Oils are widely used in aquatic feed to supply essential fatty acids and energy for the fish. However, the abundance of unsaturated fatty acids makes oils susceptible to be oxidized, resulting in harmful effect on the health of fish. To investigate the effect of dietary oxidized oils on the growth performance, body color and antioxidant capacity in liver of channel catfish, Ictalurus punctatus, six isonitrogenous and isolipidic diets were prepared to feed channel catfish (150.5±4.2) g. The six diets were designed with 6% supplementation level of fish oil (FO-6), soybean oil (SO-6), mixed oil (3% fish oil + 3% soybean oil, MO-6), oxidized fish oil (OFO-6), oxidized soybean oil (OSO-6), oxidized mixed oil (3% oxidized fish oil + 3% oxidized soybean oil, OMO-6), respectively. After 8 weeks feeding, the fish fed FO-6, SO-6 or MO-6 diet showed no differences in weight gain (WG), feed conversion ratio (FCR), muscle composition, body color and antioxidant indicators in liver (P>0.05), which indicated that soybean oil could completely substitute the inclusion of fish oil in the diet of channel catfish. The WG and muscle lipid level of the three oxidized oil groups were significantly lower, andFCR, skin yellowness, liver malondialdehyde content, and total bilirubin, direct bilirubin, alanine aminotransferase, aspartate aminotransferase in serum were significantly higher (P<0.05) than that of the normal oil groups. The activities of catalase and superoxide dismutase, and the glutathione contents in liver were reduced by dietary oxidized oils (P<0.05), but the dorsal muscle color and moisture, crude protein, ash content in flesh were not affected (P>0.05). The above results showed that 6% oxidized oils (fish oil, soybean oil, or mixed oil) reduced the growth performance, increased the yellowness of skin and damaged the antioxidant capacity of liver of channel catfish. Soybean oil could completely replace the fish oil inclusion in the diet of channel catfish.
Available online   , doi: 10.7541/2018.007
[Abstract](62) [FullText HTML](28) [PDF 547KB](8)
Abstract:
A 80-day feeding trial was conducted to assess the interactive effects of β-glucan (BG) and Heat-killed Lactobacillus plantarum (HK-LP) on growth performance, intestinal fatty acid composition, and immune function of juvenile loach Misgurnus anguillicaudatus. Fish [average initial weight of (0.17±0.01) g] were fed with six experimental formulated diets containing two levels of BG (0% and 1%) with three levels of HK-LP (0.025%, 0.05%, and 0.1%) in triplicate. Results showed that supplementation of BG and HK-LP increased the body weight gain, specific growth rate, while significantly reduced the feed conversion ratio of fish. However, interaction between BG and HK-LP showed no significant effect on those parameters. Supplementation of BG remarkably decreased the percentage of C16 鲶1n-7 and C18 鲶2n-6 in intestinal fatty acid composition. Meanwhile, the percentage of C22 鲶1n-11 was decreased by dietary HK-LP. Dietary BG, HK-LP and two-factor interactions significantly influenced the activities of alkaline phosphatase (AKP) from skin mucus. Increase of dietary BG and HK-LP levels enhanced the activities of lysozyme. Supplementation of dietary 1% BG and 0.05% HK-LP significantly increased the expression levels of Hsp70 and Hsp90α. Therefore, the addition of BG and HK-LP in the diets could improve the growth performance of juvenile loach, and in the experiment, the optimum level of BG and HK-LP in the loach diet was 1% and 0.1%, respectively.
Available online   , doi: 10.7541/2019.006
[Abstract](242) [FullText HTML](126) [PDF 648KB](23)
Abstract:
In order to provide biological information for research on sex-determination mechanism in Pelodiscus sinensis, we here first attempted to clone and analyze the partial-length of Foxl2 cDNA. In addition, to address the differential expression of Foxl2 at genetic and physiological levels, both male and female sexes of Pelodiscus sinensis were treated with 10 mg/kg E2 and 17α-methyltestosterone (MT), respectively; Foxl2 mRNA expression was quantitatively examined in the gonads after injection treatment at 6, 12, 24, and 48h, as well as 7 and 14d, respectively. Foxl2 (GenBank Accession No.KP734210) was achieved, belonging to Forkhead family of transcription factors that is involved in ovarian development and functional maintenance, as well as a 903 bp of open reading frame (ORF) encoding 300 amino acids. Multiple sequence alignment showed that Foxl2 contained typical FH-domain, and the most similar ortholog was Trachemys scripta, reaching up to 99%. Stability analysis of phylogenetic trees showed that Pelodiscus sinensis Foxl2 was clustered with reptile Foxl2 as a sub-branch, and was closely associated with Foxl2 from Chrysemys picta bellii. Results of quantitative reverse transcription PCR (RT-qPCR) indicated that, compared to the control group, E2 significantly up-regulated Foxl2 mRNA repression in ovary after 24h (P<0.001), which in testis was significantly increased after 7 and 14d (P<0.001). MT treatment strongly and equally up-regulated expression levels ofFoxl2 mRNA in ovary and testis at 24h (P<0.001). These results suggested that E2 and MT could up-regulate Foxl2 expression. Moreover, the sex differences in E2 promoting Foxl2 expression is more significant than MT. It can be concluded that the present research contributes to better understanding of the functional role of Foxl2 and provide basic data for further study on how exogenous hormone mediates Foxl2 in Pelodiscus sinensis.
Available online   , doi: 10.7541/2019.005
[Abstract](50) [FullText HTML](30) [PDF 784KB](6)
Abstract:
Three variants of EcHcL1 and 2 based on Exopalaemon carinicauda transcriptome library were obtained by using RACE technique. The total length of EcHcL1 and 2 were 2248 bp and 2121 bp, which encoded protein of 685 and 676 amino acids, respectively. EcHcL1 and 2 are relatively conservative in evolution, and has typical domains of hemocyanin, including copper ion binding region, conserved His site and Ig-like region. EcHcL1 may relate to pigment metabolism and phenoloxidase activity because of more than a tyrosinase domain. The results of tissue expression distribution showed that EcHcL1, 2 were expressed in all the 10 tissues, and higher expressed in hepatopancreas and haemocytes. Different variants of E. carinicauda hemocyanin subunit may also have various immunological functions. The expression of the 2 variants of mRNA after pathogen stresses were investigated using the Real-time PCR strategy. The results showed that EcHcL1 had higher expression level during 12—48h after Staphylococcus aureus, Vibrio parahaemolyticus and WSSV challenges, and its among more 1.5—4 times higher than that in control group. The expression level of EcHcL2 reached the highest value among 24—48h after stress, which increased 2—9 times compared with the control group. Therefore, we speculated that the E. carinicauda hemocyanin subunit variants may related to immune defenses closely and might have antimicrobial resistance activity.
Available online
[Abstract](319) [FullText HTML](132) [PDF 645KB](50)
Abstract:
The Yangtze floodplain is one of the most important wetlands in the world. For decades, many lakes in this region have suffered from multiple stressors, such as over-exploitation fishery resources and cultural eutrophication. To solve these problems, it is necessary to establish a quantitative lake ecosystem management platform at a regional scale. Recognizing the lack of regional scale zoobenthos models with high predictive power, we carried out 105 lake-time investigations on 46 small-to medium-sized lakes along the mid-lower Yangtze River in this study. The results showed that the density and biomass of zoobenthos of these lakes were (847±248) ind./m2 (mean±SE) and (29.41±3.97) g/m2, respectively. The density and biomass of oligochaetes, gastropods and chironomids were (403±225) ind./m2 and (1.12±0.39) g/m2, (82±20) ind./m2 and (26.38±3.99) g/m2, and (356±62) ind./m2 and (1.86±0.58) g/m2, respectively. Further analyses showed that water depth, Secchi depth, water temperature, total phosphorus, phytoplankton chlorophyll a, and submersed macrophyte biomass were the important factors affecting the standing crops of zoobenthos. A series of models were therefore established. The explanation of variations in zoobenthos density among lakes was generally better than that of biomass. The explantion percentage of simple regression models were between 18%—33% for density and 7%—18% for biomass. In the multiple regression models, the explanation percentage was 46%—49% for density and 16%—55% for biomass. Considering the large sampling size of this study, the explanation of these research models was significantly higher than that of previous studies. When comparing the percentage predictive errors (PPE), the simple models and multiple models showed similar results: PPE was 76%—171% for density and 115%—1034% for biomass in simple models, and 88%—114% for density and 141%—1015% for biomass in multiple models. Therefore, these simple regression model with relatively few variables and good predictive power are suggested in practical application.

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2018, 42(6): 1075 -1080   doi: 10.7541/2018.132
[Abstract](253) [FullText HTML](109) [PDF 360KB](24)
Abstract:
Asian carp are expanding their range throughout the Mississippi River; however, abundance is thought to be highest in reaches within close proximity to the Illinois River. In the Mississippi River, Lock and Dam 19 (L&D 19) at Keokuk, Iowa is the primary barrier to slow the expansion upstream. As Asian carp abundance increases below L&D 19, it is important to investigate potential means of control (i.e., reduction through harvest and barriers) that will prevent complete invasion of the Mississippi River above L&D 19. Silver Carp and Bighead Carp were collected below L&D 19, a subsample were implanted with ultrasonic transmitters to evaluate passage through the lock chamber and the remainder were used to determine population dynamics at the leading edge of invasion. Although the dam portion of the structure poses a complete barrier to upstream expansion, we documented lock chamber passage demonstrating the lock chamber has the capability to provide passage upstream. Based on the results of the population assessment, in order to induce recruitment overfishing at this leading edge of invasion, Asian carp will need to be intensively harvested at 300 mm and larger. The combination of commercial fishing efforts and research investigating ways to prevent passage upstream must be employed.
2018, 42(6): 1081 -1083   doi: 10.7541/2018.133
[Abstract](287) [FullText HTML](109) [PDF 190KB](24)
Abstract:
Silver carp Hypophthalmichthys molitrix were introduced into the U.S. to control water quality in aquaculture ponds. From this point of origin, silver carp escaped into nearby rivers through multiple flood events. Because of their documented negative effects on native biota, silver carp have been labeled as problematic. Therefore, evaluating the biology and ecology of these non-indigenous species is critical. Multiple parameters are needed to evaluate silver carp populations (length, weight, age, and sex). Furthermore, developing methods for rapidly acquiring these data are needed. In relation to sex determination, sexual dimorphism was observed where males exhibit distinct pectoral fin ray features. Specifically, males have pronounced ridges or a " rough patch” on the dorsal surface of pectoral fins. Therefore, to test if this was an applicable way of determining silver carp gender; silver carp were collected from Midwestern U.S. rivers (N=2015) in the fall of 2011 (N=870), spring of 2012 (N=645), winter of 2013—2014 (N=202) and summer 2015 (N=323) via electrofishing. For each silver carp collected, presence (e.g., rough patch) or absence (e.g., smooth) of pronounced ridges on the top side of the pectoral fins was recorded, and an incision was made in the body cavity to identify gender. Based on the results of our evaluation, gender was correctly identified over 99% of the time (2006 out of 2015) based on the pectoral fin dimorphism. In the samples taken in the winter of 2013—2014 and summer of 2015, accuracy for silver carp shorter than 300 mm and longer than 800 mm was 53.7% (19 out of 41) while accuracy for silver carp between 300 mm and 800 mm total length was 98.9% (289 out of 292). This study provides a rapid assessment approach for evaluating silver carp gender.
2018, 42(6): 1084 -1088   doi: 10.7541/2018.134
[Abstract](258) [FullText HTML](98) [PDF 321KB](13)
Abstract:
The establishment of a highly efficient planktivore, Silver carp (Hypophthalmichthys molitrix), in the Mississippi River Basin has been documented as having negative impacts on native planktivore populations. Silver carp have the potential, to alter the trophic food web through negative interactions with native planktivores in large river systems. Due to increasing Silver carp ranges, interactions between Silver carp and other native planktivores is likely to increase. One abundant native planktivore that is often found in similar habitats as Silver carp is Gizzard shad (Dorosoma cepedianum). Potential competition for resources exists because of overlapping habitat use and forage. Given the similarities between these two planktivores, we sought to evaluate daily growth rates and determine hatch dates of age-0 Silver carp and Gizzard shad in the Middle Mississippi River. Silver carp and Gizzard shad were collected from the Middle Mississippi River using an electrified surface trawl from June through September with sizes ranging from 21—65 mm total length for Gizzard shad and 24—85 mm total length for Silver carp. A sample of age-0 fish (n=697) was collected at the end of the growing season including 292 Gizzard shad and 405 Silver carp. Size structure (total length in mm) of Silver carp (49.05±0.41; \begin{document}$\overline {{{X}}}$\end{document} ± SE) was significantly greater (T= –16.43, df=695, P<0.001) than Gizzard shad (38.95 ± 0.45). Hatch dates were similar between Silver carp (July 26th to August 18th) and Gizzard shad (July 28th to August 19th). Growth of Silver carp (2.24 mm per day) was significantly greater (P<0.001,T= –11.1, df=82) than Gizzard shad (1.72 mm per day). Mortality was similar between Silver carp (28.1%) and Gizzard shad (25.1%) at this early life stage. The faster growth rates in Silver carp result in Silver carp entering the winter season larger in size with likely an increased capacity to consume plankton and decreased predation ultimately leading to higher recruitment. Knowing that there exists an overlap between Silver carp and Gizzard shad diets and habitat could alone call cause for concern. Adding that spawning occurs at a similar time and Silver carp have the ability to outgrow Gizzard shad early in life leads to major concerns about food web balance. Knowing that invasive planktivores have already shown to alter food webs in aquatic systems in North America, extra caution should be taken.
2018, 42(6): 1089 -1106   doi: 10.7541/2018.135
[Abstract](525) [FullText HTML](173) [PDF 624KB](18)
Abstract:
The lower Mississippi River (LMR) has been heavily modified for multiple human purposes such as navigation, flood control, and bank stabilization. However, the LMR simultaneously supports a diverse fish fauna that includes recreational and commercial fisheries. Due to river training and diversion structures constructed during the past 80 years, the historic characteristics of the LMR have been drastically altered and have likely influenced fishes and fisheries in the system. One common restoration measure used throughout the LMR has been to " notch” wing-dike structures that close secondary (side) river channels. Dike notching allows year-round flows through secondary channels, which enhances habitat diversity and promotes biological productivity at the ecosystem scale. Although notching is presumed good for LMR fishes and other biota, few studies have examined its effects on fish assemblages. In this study, fish assemblages were sampled at seven LMR secondary channels spanning from river kilometer (rkm) 628 (Louisiana-Mississippi, U.S.A.) upstream to rkm 1504 (Missouri-Kentucky, U.S.A.). Four secondary channels were termed " permanent” (i.e., with notched dikes) while three secondary channels were termed " temporary” (i.e., without notched dikes). Fishes were sampled by boat-mounted electrofishing conducted during falling and low stages from 1995—1997. Fish assemblages differed between permanent and temporary secondary channels, and varied somewhat between falling and low stages. Gizzard shad (Dorosoma cepedianum), threadfin shad (D. petenense), and white bass (Morone chrysops) demonstrated consistent preferences for low-current conditions associated with temporary secondary channels. Conversely, blue catfish (Ictalurus furcatus), flathead catfish (Pylodictis olivaris), and freshwater drum (Aplodinotus grunniens) were more associated with permanent secondary channels. Future restoration strategies in the LMR should consider dike notching and resultant maintenance of permanent secondary channels in selected river reaches. However, temporary secondary channels also contain unique fish species, and also appear to be important sites of riverine primary production. Restoration strategies should consider a balance of both secondary channel types, which should support the greatest biodiversity for the LMR ecosystem.
2018, 42(6): 1107 -1115   doi: 10.7541/2018.136
[Abstract](195) [FullText HTML](92) [PDF 528KB](13)
Abstract:
Knowledge of the vulnerability of different species and size groups to various types of fishing methods is vital to the development of optimal harvesting strategies and rational exploitation of fish resources. In this study, the selectivity of four types of fishing methods (weir nets, gill nets, electrofishing, and cormorants) used simultaneously in a typical multi-species shallow lake (Lake Niushan, China) within the Yangtze River basin, was compared for catch composition, efficiency, and size selection. Species selectivity was evaluated with the index of relative importance (IRI). Potential fishing effects on the trophic structure of fish community were analyzed by calculating the mean trophic level (MTL) of the catches and the weight ratio between prey and predator fishes. Results indicated that the use of weir nets and electrofishing should be reduced or eliminated, because they were relatively unselective and caught many species, including juvenile individuals. Fishing efforts of cormorants should be restricted due to their high fishing efficiency, especially on piscivorous fishes. Gill nets with appropriate mesh size are likely to be a more sustainable fishing method since they were more selective in capturing larger individuals and could balance the prey-predator relationship. We suggest shifting from single-species approaches toward multi-species management, and taking trophic interactions into account to better manage fishery resources.
2018, 42(6): 1116 -1123   doi: 10.7541/2018.137
[Abstract](176) [FullText HTML](84) [PDF 463KB](8)
Abstract:
To assess possible bias of different fishing methods is essential to appropriate fisheries management. In the current study, fish assemblage structure of a shallow Yangtze River lake was assessed by combining one international standard sampling gear (multi-mesh gillnet), and one traditional Chinese gear (the dense-mesh weir). Using Lake Biandantang as a case study, a total of 27 fish species were collected from the two gears combined, including 2 new species that had not been recorded previously in this lake. Results suggested that fish assemblages had changed greatly compared to a previous study conducted in the 1990s. Specifically, differences were found in species composition, abundance, biomass, and length distributions collected from the two gears. Difference in total length (TL) distributions of fishes caught was the most conspicuous change. Fishes collected from the weir ranged from 40—70 mmTL, whereas fishes collected from gillnets ranged from 90—140 mmTL. Multivariate ordinations based on relative abundance and biomass data also indicated fish assemblage structural differences between the two gears. The comparative results showed that the multi-mesh gillnet was effective at assessing fish assemblages in shallow lakes, such as those found along the middle and lower reaches of the Yangtze River. Additionally, assessments using only one gear could have some limitations with respect to interpreting fish assemblage changes over time.
2018, 42(6): 1124 -1134   doi: 10.7541/2018.138
[Abstract](164) [FullText HTML](82) [PDF 575KB](16)
Abstract:
We analysed spatial pattern in the fish assemblage structure along a longitudinal gradient of the Upper Yangtze River and the Three Gorges Reservoir. We tested the hypothesis that shifts from lotic to lentic environment affect the richness and structure of the fish assemblage. Samplings were carried out from 2005 to 2012 in four zones:(1) Hejiang reach, river upstream from the reservoir; (2) Mudong reach, upper part of the reservoir; (3) Wanzhou reach, middle part of the reservoir, and (4) Zigui reach, lower part of the reservoir. A total of 368706 fish representing 132 native species of 17 families were collected during the study period with Cyprinidae as the dominant group. The results showed that the native species richness decreased while the non-native species increased from river (Hejiang reach) to reservoir (Zigui reach). Patterns in fish assemblage ordination evaluated by correspondence analysis reflected a clear division of the riverine and reservoir zones. Uppermost sampling stations were characterized by species characteristic of flowing waters, whereas in the lowland most lentic species were captured. Further, 22 species, three functional groups (rheophilic, equilibrium, insectivorous) were identified for the upper reach and 16 species, three functional groups (herbivorous, planktivorous, stagnophilic) for the lowland reach by indicator species analysis (P<0.05). Therefore, it is evident that impoundment of the Three Gorges Reservoir is the major driving factor to structuring the fish assemblage structure along the longitudinal gradient from river to the reservoir. Different fisheries management actions should be made to conserve or rehabilitate native fish assemblages and control invasive non-native species.
2018, 42(6): 1135 -1143   doi: 10.7541/2018.139
[Abstract](237) [FullText HTML](102) [PDF 482KB](14)
Abstract:
There is limited information available on effects of aquaculture on lake ecosystems. Community structure and biodiversity of phytoplankton were investigated from July to September, 2015 in 23 lakes in the middle reach of the Yangtze River Basin, which include four groups: reservoir group (A), aquaculture ban group (B), low stocking aquaculture group (C) and high stocking aquaculture group (D). The analysis showed that dominant genera of the four groups were different. Group A was dominated by Pseudanabaena (Y=0.642) and Planktolyngbya (Y=0.064). Group B was dominated by Merismopedia (Y=0.428), Planktolyngbya (Y=0.118), Pseudanabaena (Y=0.133), and Scenedesmus (Y=0.066). Group C was dominated by Pseudanabaena (Y=0.395), Merismopedia (Y=0.097), and Planktolyngbya (Y=0.122). Group D was dominated by Merismopedia (Y=0.308), Microcystis (Y=0.118), and Pseudanabaena (Y=0.077). The phytoplankton abundance in group A was significantly lower than those in other lake groups (P<0.05). There was no significant difference in Shannon-Wiener index, Margalef index and Pielou index of phytoplankton among the four lake groups. The study indicated that fish culture could affect the abundance and dominant genera of phytoplankton, which may provide some implications for lake ecosystem management.
2018, 42(6): 1144 -1152   doi: 10.7541/2018.140
[Abstract](99) [FullText HTML](46) [PDF 573KB](9)
Abstract:
Samples of Corbicula fluminea (Müller, 1774) were collected monthly from March 2011 to February 2012 in the Datong Lake to study its population dynamics and secondary production in its native environment. A total of 4,108C. fluminea were collected and measured, with shell length (SL) ranging from 3.41 to 29.58 mm, and wet weight (WW) ranged from 0.005 to 10.03 g. The calculated SL-WW equation was log WW = –3.52+3.08 log SL (R2=0.97), which showed that the growth curve of C. fluminea followed a positive allometric pattern. The recruitment patterns peaked in one from March to April and the other one during the months of August to October. The mean annual abundance and biomass ( \begin{document}$\bar B$\end{document} ) were (274±95) ind./m2 and (20.1±5.7) g AFDW/m2 (Ash Free Dry Weight, AFDW), respectively. The annual secondary production (P) was estimated to be 23.90 g AFDW/m2·year, resulting in a P/ \begin{document}$\bar B$\end{document} ratio of 1.20/year and a turnover time of 298 days. The asymptotic maximum length (L), curvature parameter (K) and seasonal oscillation in growth rate (C) derived from the von Bertalanffy Seasonal Growth Formula (VBSGF) were 31.91 mm, 0.45/year, and 0.84, respectively. The slowest growth period was in January, and the potential lifespan (tmax) was estimated to be 4.44 years. The total mortality (Z), natural mortality (M) and fishing mortality rates (F) estimated were 1.68/year, 0.89/year and 0.79/year, respectively. Its exploitation rate (E=0.47) indicated a slightly high exploited stock that needs some management intervention to maintain the sustainability of this fishery resource.
2018, 42(6): 1153 -1162   doi: 10.7541/2018.141
[Abstract](180) [FullText HTML](73) [PDF 1022KB](16)
Abstract:
A comprehensive investigation on macrophyte community in Hongze Lake was conducted seasonally from May 2010 to February 2011. Overall, twelve species representing eight families of macrophytes were identified in Hongze Lake, including nine species of submerged plants, two species of floating-leaved plants, and one species of emerging plant. In general, Potamogeton malaianus, P. maackianu, P. pectinatus and P. crispus were the four dominant species throughout the whole year, the highest biomass of macrophytes was presented in autumn, followed by summer and winter, while spring had the lowest biomass of macrophytes. Based on field data, we used kriging interpolation in ArcGis to map the spatiotemporal distribution of the entire macrophyte community as well as each of the four dominant species. From the GIS maps we observed that the northern area of the lake, namely the Chengzihu region, had the highest biomass of macrophytes potentially as a result of better water quality and greater transparency. Potential factors that affected the community structure, biomass, and distribution patterns of macrophytes considerably were then discussed. The results of this study illuminate the need for more information on the role and importance of aquatic macrophytes in shallow lake ecosystems. Conservation of macrophytes should be taken to maintain the lake ecosystem health.
2018, 42(6): 1163 -1168   doi: 10.7541/2018.142
[Abstract](185) [FullText HTML](73) [PDF 317KB](14)
Abstract:
A tag-release-recapture study was conducted to evaluate effects of size at release on survival, growth and yield of hatchery-reared mandarin fish Siniperca chautsi fingerlings stocked in a shallow Yangtze lake. In May and June 2012, a total of 2400 juvenile mandarin fish were graded into three size groups, identified with coded wire tags and tail fin clipping, and released into Xiaosai Lake. Mandarin fish were collected after the lake drained in December 2012. Overall, a total of 973 mandarin fish individuals were captured, with an average survival rate of 40.5%. Survival rate of large sized group (63%) is more than three times higher than that of small sized group (19.5%) and 1.5 times higher than that of middle sized group (39.1%). The mean final length and weight of mandarin fish increased with the increase of release size and showed significant difference among groups. Yield was significantly affected by release size, which was the highest in large sized group and the lowest in small sized group. The net income of stocked mandarin fish increased with the increase of fish size at release. Our results indicated that mandarin fish size at release can have a major impact on success of hatchery releases, and it is suggested that the optimum release size of mandarin fish should not be less than 50 mm in Xiaosai Lake.
2018, 42(6): 1169 -1179   doi: 10.7541/2018.143
[Abstract](236) [FullText HTML](91) [PDF 586KB](18)
Abstract:
The Ptychobarbus dipogon of the Schizothoracinae subfamily, is an endemic economic fish species in Tibet Autonomous Region, China. Due to environment deterioration and invasion of alien species the population size of this species is decreasing; a study is urgently required to determine fecundity and reproductive strategy in order to conserve this natural resource. In this study, to investigate the fecundity and its relationship of body length, weight and age, we captured 1030 individuals in the middle Yarlung Zangbo River during two separate periods, one from February to March in 2013 and the other from February to June in 2014. The results showed that the standard length (SL) of males is concentrated in the 325—400 mm range, and the SL of females is above 375 mm. Sixty five females were at stages IV and V of sexual maturity, with SL 320—500 mm, weight 411.6—1328.0 g. Using the SL 50% method, the first female sexual maturity age was estimated to be 13.0 years and about 360.90 mm, while the first male maturity age was estimated to be 13.5 years and length 354.53 mm. The distributions of egg sizes, gonadal developmental stages and gonadosomatic indexes show that this species follows a synchronous spawning pattern concentrated in the period February to March, with an absolute fecundity at 3487 eggs, with a fecundity to SL ratio of 7.2 eggs/mm and fecundity to weight of 4.3 eggs/g. The absolute fecundity is positively correlated to the SL and the weight, but not significantly correlated to age. The overall male-female ratio was 1.23 鲶1. Suggestions for its conservation have been made based on its low fecundity, late maturity and short breeding period.
2018, 42(6): 1180 -1185   doi: 10.7541/2018.144
[Abstract](98) [FullText HTML](54) [PDF 435KB](5)
Abstract:
During the reproductive migration of Chinese mitten crab in the Yangtze River estuary, the relationship between fecundity and carapace width of released and wild Chinese mitten crab populations was analyzed, and then the differences between the wild and released populations were compared. The results showed that, with the increase of carapace width (CW), the fecundity (F) of released and wild population crabs increased significantly (P<0.05). In the same range of carapace width, there was no significant differences of the fecundity between the wild and released populations (P>0.05). Regression analysis showed that the relationship between theF and CW of the released population belongs to exponential function, which is F=3.979CW6.208 (R2=0.822). In addition, the relationship between F and CW of the wild population is F=1.696CW6.636 (R2=0.673). Covariance analysis showed that the curves of the wild and released crab populations fit well in significant 0.05. It could be concluded that the fecundity of the wild and released populations was at the same level. There was no significant difference between the wild and released crab population on the relationship of F and CW. The released population could reproduce well in the natural water of the Yangtze River estuary.
2018, 42(6): 1186 -1193   doi: 10.7541/2018.145
[Abstract](169) [FullText HTML](76) [PDF 465KB](10)
Abstract:
The yellow perch, Perca flavescens, is an economically significant freshwater fish species in the Midwest of the United States. TypeⅠ markers are useful for comparative mapping and other genetic analyses, but limited quantities in yellow perch. In the present study, EST containing microsatellite sequences were identified and characterized for yellow perch by data mining from updated public EST databases. Out of 21968 EST sequences of yellow perch, about 14.4% of ESTs contain repeat motifs of various types and length. CA repeat was the most abundant dinucleotides. Out of the 62 EST-SSRs for which PCR primers were designed, 15 loci showed polymorphic in a yellow perch population with the alleles per locus ranging from 4 to 19 (average 9). The observed (HO) and expected (HE) heterozygosity of these EST-SSRs were 0.103—0.929 and 0.116—0.934, respectively. Four EST-SSR loci significantly deviated from the Hardy-Weinberg equilibrium (HWE) expectation, and the remaining 11 loci were in HWE. These new EST-SSR markers should provide sufficient polymorphism for population genetic studies and genomic mapping of yellow perch.
2018, 42(6): 1194 -1202   doi: 10.7541/2018.146
[Abstract](174) [FullText HTML](88) [PDF 935KB](14)
Abstract:
The histology of gonadal development in Ptychobarbus dipogon was studied by using conventional paraffin sections and HE staining, in order to obtain information on its reproductive systems useful for its artificial breeding. The results showed that the development of oocytes can be divided into five phases, and ovarian development can be divided into six stages. In stage V ovaries, ovum worship was found to occur, indicated by the 1.38 鲶1 ratio of small ova to large ova. Phase 3 oocytes were characterized by appearance of yolk granules and follicles; phase 4 oocytes by rapid increase of yolk granules, and the movement of the nucleus toward the animal poles; phase 5 by the fusion of yolk granules, and the separation of oocytes from follicular membranes to float in the ovarian cavity. Male P. dipogen had lobular testes, and their germ cells can be categorized into spermatogonia, spermatocytes; spermatids; and spermatozoa. Their testes also developed in six stages. The species followed a batch-synchronous spawning pattern.
2018, 42(6): 1203 -1209   doi: 10.7541/2018.147
[Abstract](175) [FullText HTML](85) [PDF 498KB](15)
Abstract:
Sexual dimorphism refers to the morphological differentiation between males and females in the same population, such as sizes, morphological features, and colors. Cold water fish Glyptosternum maculatum, is an endemic teleost species of notable economic importance and with high potential for controlled rearing of the species in Tibet Autonomous Region. In this study, morphological measurements and related analysis were conducted on sexually mature G. maculatum to investigate their morphological differences in Tibet Autonomous Region. Results indicated the sexually mature populations indeed display really displayed significant sexual dimorphism: males exhibited significantly greater body length, weight, and males also exhibited in addition to greater tail length while females exhibited significantly greater eye diameter, body depth, trunk length, and lengths of dorsal, pectoral, pelvic, anal, and caudal fins at a given body length. Principal components analysis on 16 morphological parameters showed that the differences were largely due to features of the body shape (including lengths of body parts and fins) and the head, and differences in the above features differences contributed 76.7%. The t-statistic test on the allometry index b in the total length-weight function showed that during the breeding season, the total lengths and weights of G. maculatum females developed proportionally, while the male specimens were allometrical.
2018, 42(6): 1210 -1213   doi: 10.7541/2018.148
[Abstract](363) [FullText HTML](144) [PDF 295KB](25)
Abstract:
This study is based on monthly sampling (from April 2013 to April 2015) of 18 fish species representing three families. Samples were obtained using benthic fyke-nets, block nets, and multi-mesh gillnets in Lake Kuilei, a shallow lake of the Yangtze River basin, China (N 31º24′ , E 120º51′). Using ordinary least-squares linear regression, length-weight relationships of these fish species were estimated, with equations for 3 species reported for the first time. The maximum total length records of the 15 species exceeded those reported in FishBase. This paper provides new LWR equations for these species to be included in FishBase.
2018, 42(6): 1214 -1223   doi: 10.7541/2018.149
[Abstract](374) [FullText HTML](189) [PDF 689KB](24)
Abstract:
This study examined anesthetic behaviors of Schizothorax o’connori Llord in two size ranges as induced by MS-222, to acquire useful information on anesthesia of said highland fish species in out-of-water activities (surgery, labeling, measurement, etc.). Test results indicated that for both large (25.0±1.5) cm and small-sized (14.8±2.3) cm specimens, respiration rates showed no significant change in anesthetic stages Ⅰ to Ⅲ, and only begun to significantly decline after entering stage Ⅳ. The effective concentrations of MS-222 were 150—180 mg/L and 150 mg/L for two sizes, respectively. The 150—180 mg/L caused large specimens to enter anesthetic stage Ⅳ within 5min, and recovered within 5min; the 150 mg/L caused small specimens to enter stage Ⅳ within 5min, and recovered within 7min; both doses ensured a 100% survival rate after immersion for 20min. For large specimens anesthetized at 180 mg/L for 5min and exposed to air for 0—15min, there was no significant difference in recovery times (P>0.05); for small specimens anesthetized at 150 mg/L for 5min and exposed to air for 0—15min, there were significant differences in recovery (P<0.05).
2018, 42(6): 1224 -1231   doi: 10.7541/2018.150
[Abstract](169) [FullText HTML](88) [PDF 362KB](11)
Abstract:
Schizothorax macropogon and Ptychobarbus dipogon are important economic fishes in the Yarlung Zangbo River. Both are Schizothoracinaes containing a variety of essential fatty acids with high nutritional values. As food products, the textural characteristics of their meat determine important factors like taste or methods of treatment. To explore the preservation and utilization of fish resources in the Tibet Autonomous Region, China, the texture profile analysis (TPA) method was used to analyze 12 textural parameters. Fish were captured from the Yarlung Zangbo River in Shigatse and Nyingchi City. Principal component analysis showed that the texture of P. dipogon captured from the Nyingchi segment was different from the same species captured in the Shigatse segment, and different from S. macropogon captured from both segments. Factorial analysis indicated that the textural characteristics of Schizothoracinae fishes in Tibet Autonomous Region can be summarized as hardness indices, overcome attraction indices and contractility indices, of which the accumulated variance contribution rate of the first four principal component factors was 81.472%. The three categories of the four principal component axes could be the main deciding parameters of the textural characteristics of Schizothoracinae fishes in Tibet Autonomous Region. This provides scientific data for subsequent development and utilization of Schizothoracinae fishes from the Yarlung Zangbo River in different geographical areas.
2018, 42(6): 1232 -1239   doi: 10.7541/2018.151
[Abstract](208) [FullText HTML](79) [PDF 619KB](7)
Abstract:
Our study examined spatial distribution differences of rotifer resting eggs (RRE) in lakes of the Poyang Lake Wetland Area during dry season, January 2015. Field sampling was conducted in both Nanshen Lake and Baisha Lake. We found that densities of RRE in different habitats were significantly different (P<0.05), and their distribution had an obvious gradient. The highest mean density was in the marshland vegetation area of Nanshen Lake, where it was (3.34±1.28) ind./cm3. The density of resting eggs in the Zizania latifolia area was up to 5.45 ind./cm3. The density of RRE was different spatially, with the greatest in the vegetation area, then in the muddy area, and then the lowest in the water area. ANOVAs results showed that water depth, vegetation, and sediment had significant effects on RRE (P=0.001, P=0.007, P<0.001, respectively). The trend of resting egg densities in different aquatic habitats was: emergent aquatic plant > marshland vegetation > floating-leaf plants > submerged plants. The distribution of RRE in areas of different water depths was inconsistent. The density of RRE was higher in the hard than soft sediment.
2018, 42(6): 1240 -1252   doi: 10.7541/2018.152
[Abstract](456) [FullText HTML](164) [PDF 454KB](27)
Abstract:
Many efforts have been devoted to developing, constructing and refining fishways or fish passage facilities to facilitate the target fish species to pass barriers in fluvial systems. Once dominated by an engineering-focused approach, fishways science nowadays involves a wide range of disciplines from fish behaviour to socioeconomics, and to complex modeling of passage prioritization options in river networks. Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovations. After the completion of fishways construction, corresponding management systems usually need to be improved as well. In the current study, we first reviewed international fishways adaptive management systems (e.g., aspects of development, construction, and management) from 1991 to 2017 reporting on " fishway”, " fish passage”, " fish” and " dam”. The functions of fishways gradually transferred from conservation of economic stocks to overall biodiversity conservation, from facilitating upwards to both upwards and downwards passages, from developing a single project to considering the entire river basin, from fish passing function to habitats restorations as well, and from pure engineering construction to considering adaptive management. Finally, we discussed adaptive management systems and management prospects of fishways for China.

### Journal Introduction

• Establishment Time：1955  Bimonthly
• Competent unit：Chinese Academy of Sciences
• Host unit：Institute of Hydrobiology, Chinese Academy of Sciences ; Chinese Society for Oceanology and Limnology
• Editor-in-Chief：GUI Jian-Fang
• ISSN 1000-3207
• CN 42-1230/Q

Copy right © 2009 Editorial Office of Acta Hydrobiologica Sinica