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This study investigated annual variations of fish communities in different sections along the longitudinal gradient of the near-natural river based on the data collected from 2007 to 2016. A total of 134 fish species, belonged to 7 orders, 20 families and 84 genera, were collected. Among these species, Acipenser dabryanus and Myxocyprinus asiaticus have been enlisted as class Ⅰ and II protected species in China, while other 36 species endemic to the upper Yangtze River. The number of fish species increased along the longitudinal gradient, which increased from 47 in Chishui Town Section to 90 in the Chishui City Section and to 120 in the Hejiang County Section. Cluster analysis and non-metric multidimensional scaling (nMDS) ordination analysis revealed that the fish communities in all sections were varied significantly over time. The relative abundance of large and medium-sized economic fishes, such as S. sinensis and O. sima, declined continuously, while the small-sized fishes such as H. labeo, S. argentatus and R. giurinus showed the opposite trends. Additionally, the abundance of some endemic fish species, such as H. tchangi and C. guichenoti, declined markedly. The induced reasons included local overfishing, navigation, channel regulation and hydropower development, as well as changes of aquatic environment in the mainstream of the upper Yangtze River. In order to effectively protect fish stocks, it is recommended to strictly manage fisheries and water activities. Further strengthen long-term monitoring and timely detect changes in fish mix structure.
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Intermuscular bones (IBs) are common in the lower teleost and its morphology types and numbers are varied among different fish species. In this study, we documented the number, morphology, and distribution of IBs in Coilia nasus. The morphology of IBs in C. nasus was not different with Cyprinidae species; however, the distribution of IBs was quite different. Besides epineurals, epicentrals, and epipleurals, we found two others categories of IBs in C. nasus, which are located in the dorsal and ventral parts on both sides of the vertebrae. According to the reference, we called them dorsal and ventral myorhabdoi, respectively. These types of IBs were also identified in C. brachygnathus. The morphology of these IBs showed non-forked type (" 1” or " (”). The number of IBs in C. nasus ranged from 492 to 543, and the number of dorsal myorhabdoi, epineurals, epicentrals, epipleurals and ventral myorhabdoi ranged from 92 to 135 (\begin{document}$\bar x$\end{document}=114), 114 to 142 (\begin{document}$\bar x$\end{document}=133), 28 to 51 (\begin{document}$\bar x$\end{document}=42), 138 to 153 (\begin{document}$\bar x$\end{document}=142), 66 to 98 (\begin{document}$\bar x$\end{document}=89), respectively. IBs can be stained by alizarin red, but not alcian blue. For epineurals and epipleurals, the IBs were connected with one by one through connective tissues. The study identified new categories of IBs that supplement the type of IBs in teleost.
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[Abstract](34) [FullText HTML](14) [PDF 560KB](4)
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The genetic diversity of fish is seriously inferred from human disturbance factors such as water pollution and habitat destruction. Recent studies on the genetic diversity of fishes in small and medium-sized rivers in eastern China have focused on simple species, but there has been less comprehensive evaluation of fish genetic diversity and its causes. In this study, Cao’e River was selected as the representation of middle and small rivers in East China to evaluate the general genetic diversities of its fishes using mitochondrial cytochrome b gene. The results showed that the haplotype diversity indices (h) of Cyt b from the 21 species and 26 population were ranged from 0.074 to 0.987, and their nucleotide diversity indices (π) were ranged from 0.00019 to 0.00520. The genetic diversities among different species were large. Comparing the genetic diversities of fishes in different sections of Cao’s River, the haplotype diversity indices (h) of fishes decreased gradually from the estuary to upstream (P<0.05). The haplotype diversity indices (h) in species populations from Cao’e River were significantly lower than that of same species from large rivers such as the Yangtze River and Yellow River (P<0.05). The haplotype diversity indices (h) of sensitive fishes were significantly lower than those of middle tolerance fishes (P<0.05). Both the haplotype diversity indices (h) and nucleotide diversity indices (π) of three species, Pseudorasbora parva, Pelteobagrus nitidus and Mastacembelus aculeatus, in the populations from the upstream sampling site of Jinling were lower than those in the populations of same species from the sampling site of middle and lower reaches, Xianyan. This result implied that the overall genetic diversities of fishes from Cao’e River lied in middle or even low level, and that water pollution and overfishing might be the mainly reasons to reduce the genetic level of Cao’e River. In summary, our results provided an important theoretical basis for the management, protection, exploitation and utilization of fish resource of Cao’e River, and even of the middle and small rivers in East China.
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Nitrite, a common pollutant in aquaculture, is an intermediate product of nitrogen cycle in ecosystem. To explore the mechanisms of sodium nitrite-induced cell apoptosis, grass carp liver cell (L8824) were exposed to four concentrations of sodium nitrite (0, 5 mg/L, 20 mg/L and 50 mg/L) with or without treatments of phosphoinositide receptor antagonist 2-APB and IRE1 inhibitors STF-083010. Cell apoptosis related gene expression of jnk, bcl-2, bax, caspase9, caspase3, ire1α, xbp1s and grp78 and the cytoplasmic calcium ion concentration were assessed. The results showed that nitrite significantly increased the apoptosis rate, cytoplasm calcium ion concentration and mRNA levels of jnk, bax, caspase9, caspase3, ire1α, xbp1s and grp78 and significantly decreased bcl-2 mRNA level, which were reversed by the STF-083010 treatment. Besides, both 2-APB and STF-083010 reduced the sodium nitrite-induced cytoplasmic calcium ion. These results indicate that endoplasmic reticulum stress-related IRE1 pathway plays pivotal role nitrite-mediated L8824 cell apoptosis and calcium dyshomeostasis.
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[Abstract](52) [FullText HTML](23) [PDF 796KB](4)
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In order to explore the food composition of Procambarus clarkia and the food web structure in two different systems (crayfish-only system and integrated rice-crayfish symbiosis farming (IRCSF) system), we analyzed carbon and nitrogen stable isotope ratios (δ13C and δ15N) of sources and consumers, food web structure by SIBER and the food composition of P. clarkia by SIAR. The results showed that among the 19 collected species, the δ13C value of the consumer was between –34.22‰ to –25.34‰, the δ15N value was between2.33‰ to 8.05‰, and the trophic level was between1.46 to 3.64. The trophic level of P. clarkia in crayfish-only system was higher than that in IRCSF system. The metrics of food web reflected that the isotope niches in two systems using P. clarkia were similar. In IRCSF system, the trophic diversity in the food web was higher than that in crayfish-only system, and the niche overlap of each species and trophic redundancy in food web were lower than those in crayfish-only system. The significant positive correlation between the body length/weight and δ15N value of P. clarkia mean that P. clarkia prefer animal baits in two systems. The food contribution for P. clarkia was uniform and the proportion of plant baits was higher in IRCSF system compared with the crayfish-only system. The results indicated that the transfer loss of energy from sources to P. clarkia is higher in crayfish-only system, and the P. clarkia in IRCSF system was more herbivorous.
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Miniature inverted-repeat transposable elements (MITEs), a group of short and non-autonomous DNA transposons, are widely present in eukaryotic genomes. The location of the MITEs distribution would affect the host. In this study, MITEs in 33 fish genomes of the agnatha, chondrichthyes, sarcopterygii and actinopterygii were predicted and analyzed using bioinformatics approach. Ultimately, 2433 MITEs were identified in 33 fish genomes. MITEs content in 33 fish genomes varied from 0.11% to 21.18%, and MITEs content was positively correlated with fish genome size. MITEs were classified into 10 super families according to different terminal inverted repeats (TIRs) and target site duplications (TSDs) with the largest family of TC1-Mariner superfamily. The insertion of MITEs into the fish genome was mainly happened 4-0 million years ago, and most species had an explosive expansion between 2-0.5 million years ago. A number of fish MITEs were inserted into or near the genes, which may play an important role in the regulation of gene expression.
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[Abstract](44) [FullText HTML](21) [PDF 999KB](1)
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This study used Sepiella japonica as the research object to establish and optimize the acquisition method of high-turbidity water DNA (environmental DNA, eDNA) in Zhoushan offshore by absolute quantitative technique. The results indicated that the eDNA yield by ethanol precipitation method is 1.76-2.53 times higher than that of filtrating method, but the limitations of the collection volume, treatment requirement and supporting equipment make the ethanol precipitation method difficult to employ in practice. Filter screen with small aperture have no filtering effect on sediment. The size of filter aperture has a great effect on eDNA yield only when small volume water samples were collected. Precipitation treatment to water sample enhanced the yield of eDNA, but it also increased the variation of eDNA yield. Cationic surfactant significantly inhibited eDNA degradation. The effect of the membrane removal method is better than the membrane method, and it is recommended to increase the centrifugation time when the membrane removal method was used. Although the phenol extraction method can not improve the eDNA yield, it can significantly improve the purity of the product. This study is the first to establish an optimal method for obtaining eDNA of macro-organisms from Zhoushan offshore water, which provides reference for water sample collection and eDNA extraction in similar waters.
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To explore the microbial resources to control trichlorphon pollution, a potential trichlorphon-tolerant bacterium XR12 was isolated and screened from the aquaculture sediment according to the physiological-biochemical characteristics and 16S rRNA gene sequence analysis, and its antibiotic resistance and its safety and detoxification effect were evaluated. The results indicated that strain XR12 exhibited the maximum tolerance concentration of 7680 mg/L trichlorphon. The strain XR12 was identified as Rhodobacter sphaeroides through phenotypic characterization and phylogenetic analysis based on 16S rRNA sequences. Its 16S rRNA sequence had homology of 98%－100% with strains of R. sphaeroides from GenBank, and showed the closest relation to R. sphaeroides strain RSF1 (GenBank accession number: KF606891). In addition, XR12 exhibited high sensitivity to kanamycin, roxithromycin, pipram, amoxicillin, florfenicol, polymyxin B, neomycin, gentamycin, ofloxacin, enrofloxacin, norfloxacin, streptomycin, tetracycline, netilmicin, intermediate sensitivity to doxycycline and resistance to bacitracin, nalidixic acid and sulfamethoxazole. XR12 had a LC50 of >109 cfu/mL for zebra fish, and could significantly enhance the LC50 of trichlorfon to zebrafish from 26.06 mg/L to 59.51 mg/L, indicating a good detoxification effect on trichlorfon. This study indicates that XR12 had the potential for trichlorfon detoxification in aquaculture water.
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[Abstract](50) [FullText HTML](22) [PDF 3244KB](3)
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We summarize macro-patterns of macrozoobenthos in the Yangtze River Basin in this paper. A total of 1033 taxa (species/genus) belonging to 3 phyla, 7 classes, 162 families and 513 genera have been recorded from the Yangtze River Basin, including 121 annelids, 318 molluscs and 594 arthropods. In terms of taxa distributions, the species/genus number of annelids and of molluscs in the middle reaches were highest, while that of arthropods in the upper reaches was highest; the species/genus number of annelids and of molluscs in the lakes were highest, while that of arthropods in the tributaries was highest; the species/genus number of macrozoobenthos in the middle mainstem sub-basin ranked first, and that of the upper mainstem sub-basin, of the Jinshajinag sub-basin, of the Lake Dongting sub-basin and of the Lake Poyang sub-basin second. The total density of macrozoobenthos in the Yangtze River Basin was 672 ind./m2, and insects were predominant; the total biomass was 34.22 g/m2, and molluscs were predominant. In terms of standing crops distribution, the total density of macrozoobenthos in the middle reaches was the highest, the total biomass in the lower reaches the highest, while the total standing crop in the upper reaches was the lowest; the total density and biomass of macrozoobenthos in the lakes ranked first, those in the tributaries second, and those in the mainstem last; the total density of macrozoobenthos in the Lake Taihu sub-basin was the highest, and the total biomass in the Lake Poyang sub-basin was the highest. Our study indicates that the upper and middle mainstem sub-basins, the Jinshajiang sub-basin, the Lake Dongting sub-basin and the Lake Poyang sub-basin are important distribution regions for macrozoobenthos. By integrating more information of aquatic organisms, we should make comprehensive and systematic conservation plans of the Yangtze River system and implement them as soon as possible.
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[Abstract](160) [FullText HTML](58) [PDF 602KB](5)
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Myostatin propetide (MSTNpp) of Macrobrachium nipponenese was expressed in Bacillus subtilis and its effect on the growth and creatine kinase activity was investigated. The MSTNpp gene sequence was optimized to synthesize BsMSTNpp according to the B. subtilis preference codon, and the recombinant expression plasmid pGJ105-BsMSTNpp was obtained. After the transformation and fermentation of recombinant B. subtilis, the supernatant was collected and identified by Western blot. The results showed that the molecular weight of the recombinant protein was 36.0 kD. The level of recombinant BsMSTNpp increased over time, and the expression level at 100h was 10 times than that in 24h. To verify the biological activity of the recombinant BsMSTNpp, the healthy freshwater shrimp with an average body weight of 1.52 g and average body length of 4.55 cm were randomly divided into 4 groups with 3 replicates per group and 200 shrimps per replicate for a 30-days trial.The experimental group 1 and experimental group 2 were fed the basal diet supplemented with recombinant pGJ105-BsMSTNpp at the dose of 0.5×106 CFU/g and 1.0×106 CFU/g respectively. The control group 1 was fed the basal diet, and the control group 2 was fed the basal diet with pGJ105 at the dose of 1.0×106 CFU/g. The results showed that the growth ratios of the experimental groups were significantly higher than that of the control group 1 (P<0.05), and there was no significant difference between experimental groups and the control group 2. The creatine kinase activities of the experimental groups were higher than those of control groups (P<0.05). The results revealed that recombinant BsMSTNpp could enhance the activity of creatine kinase to improve the myocyte proliferation and differentiation to increase the muscle growth rate of Macrobrachium nipponenese. The results provide technical support to study the function of MSTNpp and its application in shrimp aquaculture.
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[Abstract](138) [FullText HTML](88) [PDF 530KB](3)
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To study the effects of fishmeal level and stocking density on the growth and immunity of juvenile black carp, a two-factor design of fishmeal level (10%, 20%) × culture density (50, 100, 200 tails / box) was applied. The young black carp (2.50 ± 0.02) g were divided into 6 groups of L50, L100, L200, H50, H100 and H200 with 3 replicates in each group using reservoir cages (1.5 m × 1.5 m × 1.5 m). In the early stage of experiment (week 8), the weight gain rate of black carp increased at first and then decreased with the increase of the stocking density, and the weight gain rate of the H200 group was higher than that of the L200 group (P>0.05), while it was significantly lower than that of the L200 group in the later stage (week 16) (P<0.05). The survival rate of the L200 group was lower than that of the L50 group (P>0.05). The stocking density and fishmeal levels showed an interactive effect on the survival rate and the weight gain rate (P<0.05). In the early stage, levels of lysozyme (LSZ) and serum glucose (GLU) of the low-fishmeal group decreased firstly and then increased with the increase of density, and intestinal secretory immunoglobulin A (S-IgA) increased. The levels of LSZ, complement C4, immunoglobulin M (IgM), S-IgA and cortisol of the H200 group were higher than those of the L200 group, while the GLU of the H200 group was lower than that of the L200 group (P>0.05). In the later stage, the level of C4 in the high and low fishmeal groups decreased at first and then increased with the increase of density (P>0.05). In the H200 group, the IgM and cortisol levels were higher than those of the L200 group, and the level of GLU was lower than that of the L200 group (P>0.05). In summary, high-density culture negatively regulate the growth performance, body’s immunity and anti-stress ability. The increased fishmeal level reversed the effects of high-density culture on growth performance, the immunity and anti-stress ability in the early stage. However, in the later stage, the increased fishmeal level only reduce high-density culture-mediated the survival rate without rescuing the growth performance and immune function.
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[Abstract](259) [FullText HTML](115) [PDF 2889KB](3)
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The Yangtze (Changjiang) river-floodplain is one of the most important ecosystems in China and the world, but is seriously threatened by multiple stresses. Thus, it is crucial and urgent to rehabilitate and conserve the river-floodplain. This paper reviews ecological studies conducted on the Yangtze river-floodplain, and presents suggestions for conservation and rehabilitation. First, basic concepts and research advances of riverscape and hydrological connectivity are introduced. Second, the history and current status of the Yangtze River system are summarized. Before 23 Ma, the Yangtze River cut through the Three Gorges, forming the river much like the modern one. Numerous rivers, streams, lakes (the total area 15,770 km2 at present) and wetlands are distributed in the mid-lower Yangtze river-floodplain. Such a river-lake complex ecosystem holds a unique and diverse biota, and is the most important fishery area of China. Third, main threats to the Yangtze river-floodplain ecosystem are identified, i.e., a) habitat loss, including river channelization, sharp shrinkage of lake area (ca. 10,000 km2 since the 1950s), degradation of lakeshore zones and sand over-mining; b) alternations of hydrological regimes, including construction of ca. 47,000 reservoirs and disconnection of most lakes from the mainstem; c) water pollution, including eutrophication, heavy metals, organic pollutants and microplastic; d) overexploitation of biological resources, including overfishing and intensive pen culture. Fourth, effects of river-lake disconnection on lake ecosystems are summarized. It was found that a) disconnection is one of the main causes of lake eutrophication; b) species diversity, biomass and production of macrophytes and macrobenthos reach maxima at some levels of intermediate river connectivity; c) disconnection greatly reduces fish species richness of each habitat guild, and natural fish larvae is severely depleted; d) disconnection simplifies macroinvertebrate food web structure, and trophic basis is more heavily relied on detritus in disconnected lakes. Last, conservation strategies are proposed. Since the Yangtze river-floodplain is a huge integrated system, the biodiversity conservation must be conducted on the whole basin scale. By establishing species-area models of fishes, the minimum protected area of Yangtze-connected lakes is estimated to be ca. 14,400 km2. It means that at least 8,900 km2 of disconnected lakes should be reconnected with the Yangtze mainstem, and ecohydrological operation of dams and sluices is the feasible approach. Based upon our studies on environmental flow requirements, the following measures are suggested: a) lower water levels during spring to improve germination of macrophytes, and control rising rates of water levels during spring-summer to ensure development of macrophytes; b) open sluice gates to restore migration routes for juveniles migrating into lakes during April-September, and for adults migrating back to the Yangtze mainstem during November-December.
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[Abstract](138) [FullText HTML](96) [PDF 2272KB](10)
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Nearly 90% of the hydropower resources in the Yangtze River basin are concentrated in the upper reaches of the Yangtze River. The cascaded hydropower dams and river channelization have caused habitat fragmentation and loss of fish diversity, which has aggravated the contradictions between hydropower development and environmental protection. This paper collected data on aquatic reserves (i.e. natural reserves and aquatic germplasm resources conservation zones) and cascade dams in the upper reaches of the Yangtze River, and vectorized the data in ArcGIS. Taking into account the diversity, richness and distribution of fish, we analyzed the changes in fish resources and the problems in the construction and management of the upper reaches of the Yangtze River. Therefore, several strategies have been proposed to reduce the conflicts between hydropower development and aquatic ecosystem protection, including conducting reserve census, evaluating management effectiveness of the protected areas for spatial optimization of the reserve networks, implementing the ecological restoration of essential fish habitats, implementing the rescue action plan for the upper Yangtze endangered endemic fish, establishing an efficient ecological compensation mechanism, and strengthening scientific monitoring and related research. These recommendations will provide a scientific basis for the coordinated development of hydropower exploitation and river ecological protection in the upper Yangtze River.
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[Abstract](182) [FullText HTML](82) [PDF 712KB](7)
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Tripartite motif-containing protein 25 (TRIM25) belongs to the E3 ubiquitin ligase family and plays an important role in innate immune response. To study the role of TRIM25 gene in innate antiviral immune response of large yellow croaker (Larimichthys crocea), the TRIM25 gene (named LcTRIM25) of large yellow croaker was cloned and identified. The coding sequence of LcTRIM25 gene is 2097 bp (GenBank accession numbers: MK327541), encoding 698 amino acid residues. Protein domain analysis found that LcTRIM25 contains a conserved Really Interesting New Gene (RING) domain, a B-box2 domain, a Coiled-coil domain and a variable C-terminal PRY/SPRY domain. Multiple sequence alignment and phylogenetic tree analysis showed that the LcTRIM25 gene had high homology with the Epinephelus coioides, but low homology with mammals, reptiles, amphibians and birds, indicating that the different species were under different selection pressure from environments to reach different evolutionary degrees. The results of real-time fluorescence quantitative PCR revealed that the LcTRIM25 gene was ubiquitously expressed in 9 tested issues of healthy large yellow croaker, with the highest expressions in liver and the lowest expression in heart. The expression of LcTRIM25 gene in peripheral blood, head kidney, spleen and liver were rapidly and significantly upregulated after poly (I:C) stimulation, and then decreased in all tissues. The highest expression level of LcTRIM25 gene was found at 6h in head kidney and spleen, at 12h in liver, and at 24h in peripheral blood, demonstrating that the TRIM25 gene might play a key role in the antiviral immune response of large yellow croaker. This study provides a theoretical basis for further understanding the antiviral immune mechanism of large yellow croaker.
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[Abstract](210) [FullText HTML](74) [PDF 773KB](9)
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Fibroblast growth factor receptor homolog 1 (fgfrhl-1) gene is a member of the fgfr gene family currently detected only in the genomes of fish. The sequence of fgfrhl-1 is highly conserved during fish evolution, however, the distribution of fgfrhl-1 and its specific function remains unclear. In this study, we cloned the full-length cDNA of fgfrhl-1 from two distant fish species, the grass carp, Ctenopharyngodon idellus, and the Culter alburnus, and analyzed its expression in various adult tissues. The results showed that the full-length of fgfrhl-1 cDNA sequence of grass carp was 1472 bp, containing a 213 bp 5′-UTR, a 1203 bp open reading frame and a 56 bp 3′-UTR. The full-length fgfrhl-1 cDNA sequence of C. alburnus was 1886 bp, containing a 298 bp 5′-UTR, a 1203bp open reading frame and a 385 bp 3′-UTR. The gene identified in both fish species encoded 400 amino acids, and the homology of the predicted amino acids sequences between them was 95.5%. The secondary structure prediction revealed that Fgfrhl-1 in both fish species has an intracellular tyrosine kinase domain, a transmembrane helix domain and an extracellular ligand recognizing and binding domain similar to those of FGFR, and that the extracellular domain of Fgfrhl-1 lacks three Ig-like domains that included in classical FGFRs. Semi-quantitative RT-PCR analysis explored that fgfrhl-1 was expressed in heart, gill, liver, spleen, caudal fin and intermuscular septum but not in muscle fibers in both fish species. In situ hybridization results revealed that fgfrhl-1 was expressed in connective tissues and vessels but not in the structure formed by mesenchymal cells. These results indicated the similar expression pattern of fgfrhl-1 of two different fish species mainly in the connective tissue and vessel cells of various tissues and organs, indicating that fish fgfrhl-1 may play a unique role in regulating differentiation or function maintenance of connective tissues and vessels.
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[Abstract](197) [FullText HTML](70) [PDF 1002KB](2)
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To investigate the impact of water flow on fish phototaxis, this study tested the light preference behavior of juvenile grass carp (Ctenpharyngodon idellus), adopting a self-made recirculating channel, under 300 lx light source with three velocity treatments (0, 0.1 m/s and 0.2 m/s respectively) and control group (dark, still water). The results indicated that the flow velocity of 0.2 m/s was able to adequately stimulate the rheotaxis of grass carp juveniles, constraining the dominant swimming direction within ± 20° from the opposite direction of flow. According to the distribution of juvenile grass carps in the test channel with light intensity attenuation, the illumination expectations of test fish at the three given velocity levels were 52.45 lx, 34.62 lx, and 37.86 lx respectively. During the 300 lx trial, fish in still water displayed high distribution on the lateral sides and low distribution in the middle of the channel without a preference for any specific range of light intensities. At the low-velocity level less than the induced value, the overall distribution of juvenile grass carp was similar to that in still water, but farther away from the light source, and more individuals performed " reverse flow backwards” behavior. When the flow velocity surpassed the induced value, the accumulation of fish on the rear side reduced due to the effect of the rheotaxis, and the distribution was more uniform, and the light environment influence is reduced. This study demonstrated that grass carp rheotaxis caused by a small flow velocity, which is slightly larger than the induction value, could affect its light environment response behavior.
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[Abstract](183) [FullText HTML](69) [PDF 622KB](0)
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In order to meet the demands of mandarin fish culture in different regions and seasons, and to achieve the requirement of fingerling supply of a balanced marketing, in this study, two batches broodstock were alternate artificial induced for 4 times in different seasons, and established a mode of fry and fingerling breeding by month. The results showed there were 4 peaks of gonadasomatic index for broodstock cultivated in the cage after 4 times of artificial spawning, while broodstock naturally cultivated in pond showed only 2 peaks of gonadasomatic index. The total spawning eggs and hatching fry quantity of artificial propagation were positively correlated with the peak of gonadasomatic index. The gonadasomatic index, total spawning eggs and hatching fry quantity of second artificial propagation were the highest, which were significantly higher than the other three times (P<0.05). The fertilization rate, incubation rate, fry and fingerling survival rates in second, third and fourth propagation were significantly higher than those in first propagation (P<0.05). The temperature was main factor affecting fertilization rate, incubation rate, fry and fingerling culture survival rate. The survival rate of induced broodstock decreased with increasing artificial propagation frequency. The survival rate of first propagation was up to 93.33%, significantly higher than that of third and fourth propagation (P<0.05). To sum up, it was feasible to solve the balanced supply of fingerling in mandarin fish by the modes of artificial breeding by seasonal echelon. This provides a scientific basis for changing culture mode of mandarin fish, and also has important referential significance for balanced supply of fingerling in other species.
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[Abstract](160) [FullText HTML](92) [PDF 508KB](5)
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To investigate the effects of phytase on the growth, digestibility and nutrient utilization of juvenile Chinese mitten crab Eriocheir sinensis, six diets were designed that included the control group with no phytic acid (C) and phytase and five experimental groups with 10 g/kg of phytic acid and 0, 500, 1000, 1500 or 2000 U/kg phytase that were named as P0, P500, P1000, P1500 and P2000, respectively. Juvenile crabs with an initial body weight of (4.33±0.05) g were fed with these diets for 56 days. The results showed that the weight gain rate, specific growth rate and protein efficiency of the juvenile crabs in P0 group were lower than those of the C group, and the feed coefficient was higher than that of the C group (P<0.05). The weight gain rate, specific growth rate and protein efficiency of juvenile crab increased with the increased phytase with the highest one in P2000 that had the lowest feed coefficient (P<0.05). Phosphorus content of whole crabs of P1500 and P2000 was significantly higher than that of P0 (P<0.05). P2000 had the highest trypsin activity, amylase activity in the hepatopancreas and trypsin activity in the intestine of juvenile crabs (P<0.05). The protein digestibility and phosphorus dialysis rate of Eriocheir sinensis increased gradually with the increased phytase. P2000 had the highest nitrogen and phosphorus retention rates (P<0.05). These results indicated that 2000 U/kg phytase in the diet can significantly increase the growth, protein utilization rate and trypsin activity, and reduce the feed coefficient of juvenile crabs fed the diets containing phytic acid, and promote nitrogen/phosphorus deposition rate of juvenile crabs.
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[Abstract](176) [FullText HTML](79) [PDF 870KB](8)
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As a warm-water species, changes of aquatic environment caused by global climate change could affect the distribution of Pelteobagrus fulvidraco natural resources. To investigate this (the distribution of this species in current, 2050s, and 2070s), three general circulation models (BCC-CSM1-1, CCSM4, and MRI-CGCM3), two greenhouse gas emission scenarios (RCP2.6 and RCP8.5) and random forest, an ensemble modeling, were used based on the distribution information of this species. The results indicated that the Area Under the Curve (AUC) of the prediction model reached 0.971, indicating a good generalization and great reliability; The mean temperature of wettest quarter and max temperature of warmest month were the most important environmental factors to predict the distribution of P. fulvidraco evaluated by node purity; The main habitat of P. fulvidraco would gradually depart from the eastern and middle areas in China and expand to the north, and the area of most suitable habitat would gradually decrease under the future climate change conditions. Research on the distribution of P. fulvidraco and the main ecological conditions affecting its distribution has the practical significance to delineation of germplasm reserves of P. fulvidraco, fishery management, and prevention and control for potential biological invasion, as well as provide a reference basis for the response of other freshwater fishes in East Asia to climate change.
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[Abstract](181) [FullText HTML](77) [PDF 620KB](0)
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In order to investigate the mechanism of autophagy in yellow catfish Pelteobagrus fulvidraco, we cloned P. fulvidraco LC3B (PfLC3B) and Beclin1 (PfBeclin1) genes that were 372bp and 1344bp, respectively, and constructed the plasmid pET32a(+)-PfLC3B and pET32a(+)-PfBeclin1 encoding recombinant PfLC3B and PfBeclin1 protein, respectively. The recombinant PfLC3B was highly purified by affinity chromatography, while the recombinant PfBeclin1 protein was highly purified under inclusion body conditions. The polyclonal anti-PfLC3B and anti-PfBeclin1 antibodies were generated by immunizing Balb/C mouse with recombinant PfLC3B and PfBeclin1 protein, respectively. The results of western blot showed that the polyclonal anti-PfLC3B and anti-PfBeclin1 antibodies could recognize recombinant and endogenous PfLC3B and PfBeclin1 protein, respectively. PfLC3 and PfBeclin1 were predominantly expressed in the liver, but not in the kidney and spleen. In conclusion, we generated polyclonal anti-PfLC3B and anti-PfBeclin1 antibodies, which provided powerful tools to investigate the mechanism of autophagy in yellow catfish.
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[Abstract](152) [FullText HTML](86) [PDF 1233KB](2)
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Sinibotia reevesae, an endemic fish, lives only in the upper reaches of the Yangtze River. This study explored the structure characteristics of Sinibotia reevesae brain and effects of the ecological habits on the central nervous system. The results showed that S. reevesae brain was composed of five parts of telencephalon, diencephalon, mesencephalon, cerebellum and myelecephalon. The olfactory lobe was a typical spindle shape and the preoptic nucleus of the brain was arranged in a cord-like manner without large preoptic nucleus and small cell group. The corpus mamillare and parasympathetic nucleus were visible in the diencephalon, meanwhile, saccus vasculosus and inferior lobeis were well developed. There were five layers in the tectum opticum of the mesencephalon and three layers in the cerebellum. The myelecephalon located in the end of the brain and differentiated into facial lobes and developed vagal lobes. Histological observations revealed that olfactory, auditory, tactile sensation, taste, motor centers and athletic ability of S. reevesae were well-developed. To sum up, the S. reevesae mainly depend on the sense of smell, hearing, touch, and taste to forage and to evade the natural enemies.
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[Abstract](149) [FullText HTML](93) [PDF 686KB](1)
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In order to understand the status of fish resources in Shaanxi Province of the Weihe River, we conducted a survey on fish resources in the Shaanxi section of the Weihe River in four times from 2016 to 2017. A total of 49 species of fish were investigated, which belong to 6 orders, 11 families, 36 genera. The dominant species were Gnathopogon imberbis, Rhynchocypris lagowskii, Abbottina rivularis, Hemiculter leucisculus, Cyprinus carpio and Hypophthalmichthys molitrix. Compared with the results of the survey in 1984, 36 species of fish were reduced with a significant decrease of the variety of species. The similarity index of species composition between two investigations was 0.49, representing a medium dissimilarity. According to Shannon-Wiener index, Pielou’s index, Marglef index, Jaccard’s index and G-F index, the composition of Fishes community was obviously changed in the Weihe River of Shaanxi section, and the species diversity decreased by 60%. The analysis of the individual ecology type indicated that the community structure in Weihe Shaanxi section has changed greatly, which are mainly composed of slow flow, omnivorous type, and inhabiting gravel substratum group. The results indicated that the diversity of fish species and the amount of fish resources in the river have decreased significantly, which may explain by the water pollution, decreased water resources and reduced habitat suitability.
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[Abstract](155) [FullText HTML](81) [PDF 976KB](0)
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Anqing section is one of the important fishery resources waters in the lower reaches of the Yangtze river. To understand assemblage characteristics of larvae and juveniles fish and their correlation with environmental factors, the early fish resources in Anqing section were investigated day by day from April 17 to August 15, 2016. The results revealed that a total of 92160 larvae or juveniles were captured, and 90457 were identified, belonging to 7 orders, 13 families and 49 species, while Cyprinidae was the largest family including 32 species, accounting for 90.16% of the total number of tails; Gobiidae was the second largest family including 3 species, accounting for 5.71% of the total number of tails. As for ecological type and spawning type, fishery residents fishes and fishes with pelagic eggs accounted for the largest proportions of 87.57% and 88.30%, respectively. Hemiculter bleekeri (44.53%) was the largest dominant species in this section and the other dominant species were Hemiculter leucisculus (14.21%), Xenocypris argentea (8.11%), Rhinogobius giurinus (5.60%), Pseudolaubuca sinensis (4.75%), Pseudobrama simoni (4.13%), Pseudolaubuca engraulis (4.50%), Parabramis pekinensis (2.63%), Coilia nasus (1.89%) and Hypophthalmichthys molitrix (1.57%). Larvae or juveniles abundances have four obvious outbreak period with the first period on May 1st and the other three in the mid to late June, which were 1127.00, 1608.44, 1568.44, 1202.94 ind./100 m3, respectively. Redundancy analysis (RDA) revealed that the main environmental factors affecting the abundance of larval and juvenile fish in Anqing river section are water flow, water level and transparency (P < 0.05). The abundance of most larval and juvenile fish were negatively correlated with water flow and water level, and positively correlated with transparency, which may explain by the excessive water flow and water level in that year. This study demonstrated that Anqing section was abundant of diverse species of early fish resources which mainly consisted of small fish, and the proportion of economic juvenile fish is small. These results provide basic information for the formulation of protection policy on Anqing fishery resources with scientific reference.
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[Abstract](177) [FullText HTML](65) [PDF 972KB](4)
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The DMRT1 (double sex and mab-3 related transcription factor 1) is a highly conserved transcriptional regulator to play important role in sex determination and differentiation in most species ranging from nematodes to mammals. In this study, we cloned the cDNA sequence of dmrt1 from peanut worms cDNA library by RACE-PCRs. The full-length dmrt1 cDNA was 1509-bp with a 615-bp open reading frame (ORF) encoding a protein of 204 amino acids. Bioinformatics analysis showed that peanut worms DM domain shared high homology (>70%) with those of other vertebrates as well as the invertebrate marine mollusks DMRT1. Dmrt1 was abundantly expressed in coelomic fluid of male peanut worms, where existed the germ cells. In situ hybridization explored positive dmrt1 signals in the trophoblast cells. These results suggest that dmrt1 may play important role in male germ cell development, and reproductive regulation in spermatocyte maturation of peanut worms.
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[Abstract](161) [FullText HTML](75) [PDF 524KB](2)
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To quickly and effectively distinguish different families and pedigrees of Coreius guichenoti, the present study screened twenty microsatellite loci with high polymorphism and stable amplification from the reported forty microsatellite loci using 339 individuals from eight families of C. guichenoti. Through this study, a paternity technology combined with fluorescent microsatellites and multiple capillary electrophoresis in C. guichenoti were established. Genetic diversity analysis revealed that the average allele number (Na) of eight families of C. guichenoti, the average polymorphism information content (PIC), the average expected heterozygosity (He), and the average observed heterozygosity (Ho) were 9, 0.616, 0.659, and 0.691, respectively. Genetic diversity indices of the offspring group were significantly lower than those of the parent group. Parentage analysis revealed that the combined exclusion probability of both unknow parents (CE-1P), single unknow parents (CE-2P) and both know parents (CE-PP) were 0.999 544 73, 0.999 998 25 and 1.000 000 00, respectively, indicating that the accurate rate of parentage assignment was 100%. Thus we established a reliable paternity technology of C. guichenoti, which can provide scientific basis for its genealogical management, population genetic management, and assessment of stock enhancement effect.
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[Abstract](164) [FullText HTML](61) [PDF 1339KB](1)
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The steady growth of submerged plants is an important factor for the reconstruction of healthy lake ecosystem, and the sediment conditions are also the key factors for the growth of submerged plants. This study explores the effects of medical stone on its physiological and ecological changes in submerged plants. The results showed that the medical stone significantly promoted the growth of Vallisneria natans. The height and biomass of Vallisneria natans covered with 1cm thick medical stone were better compared with the lake sediment group (P<0.05), and the modified medical stone group was better than the raw stone group (P<0.05) to promote the height and biomass of Vallisneria natans. The photosynthetic pigment, root activity, malondialdehyde (MDA), peroxidase (POD) activity and other indicators of the two plants, Vallisneria natans and Hydrilla verticillata in medical stone group were better than those in the lake sediment group. The medical stone contained abundant constant and trace elements that are required for the growth of submerged plants. Thus, medical stone is beneficial to the growth of submerged plants and can be further applied to ecological restoration projects as sediment improvement material.
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[Abstract](339) [FullText HTML](124) [PDF 1050KB](7)
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To reveal the relationships between spawning activities of pelagophil fish and environmental factors in the Three Gorges Reservoir (TGR), fish eggs and larvae were sampled at Zhongxian section, from May to July in 2016 and 2017. 60 fish species including 30 pelagophil fishes were sampled. Hemiculter bleekeri and Squalidus argentatus were the dominant species in eggs, and Hemiculter and Pseudolaubuca were abundant in larvae. In 2016, 7.041 billion eggs and 103.763 billion larvae drifted through the sampling section, and in 2017, 3.454 billion eggs and 34.427 billion larvae drifted through the sampling section. The amount of eggs and larvae of the four major Chinese carps reached 2.909 billion in 2016 and 2.117 billionin in 2017. Spawning activities of pelagophils fish varies temporally in different river reaches, which mainly occurred after early-June in the river reach from Zhongxian to Fuling but begun in mid-May in the river reach upstream of Changshou. Fish eggs and larvae from the river reach upstream of Changshou provided a large resource for recruitment to the fishery in TGR. Classification and regression trees (CART) analysis explored that spawning activities of the four major Chinese carps were favord when water discharge was rasing. But, spawning activities of Hemiculter bleekeri and Squalidus argentatus had no relationship with water discharge. In order to protect the spawning grounds and meet environmental requirements for natural reproduction of pelagophils fish, we propose ecological regulation of the cascade hydro-power projects in the Jinsha River and maintenance of large free-flowing stretches upstream of TGR.
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[Abstract](356) [FullText HTML](104) [PDF 762KB](1)
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Phospholipase A2 plays a role in physiological and pathological processes such as phospholipid metabolism, inflammatory response, cell proliferation, and atherosclerosis. To investigate the biological function of sPLA2-III, five Ccpla2g3 paralogous genes located on different linkage groups were identified from the common carp (Cyprinus carpio) whole-genome using BLAST and synteny analysis performed by Genomicus, which named as Ccpla2g3a1, Ccpla2g3a2, Ccpla2g3b, Ccpla2g3c1 and Ccpla2g3c2, respectively. Gene structure and sequence analysis showed that Ccpla2g3as contained 7 exons, whereas Ccpla2g3b and Ccspla2g3cs contained 4 exons. These five genes respectively encoded 530, 525, 461, 752 and 753 amino acids, and all contained the PLA2_bee_venom_like region and characteristic sequences of sPLA2-III. Synteny analysis indicated that Ccpla2g3a1, Ccpla2g3a2, Ccpla2g3c1 and Ccpla2g3c2 were from the specific genome duplication of common carp. During evolution, the pla2g3a (b) in 2R (two rounds of genome duplication) fish, spotted gar (Lepisosteus oculatus) duplicated to pla2g3a and pla2g3b in 3R (fish-specific genome duplication, FSGD) fishes such as zebrafish (Danio rerio), but there was only one pla2g3c gene in 3R fishes because the other copy on the duplicated chromosome was lost. Homology analysis showed that the similarities of Pla2g3as, Pla2g3bs and Pla2g3cs of the analyzed fishes in orthologous proteins were 48.8%—93.2%, 37.6%—74.3% and 49.6%—97.6%, respectively, with the highest one between common carp and zebrafish. Phylogenetic analysis showed that Pla2g3cs of teleost’s and their ancestor, spotted gar, were grouped within the same branch with a bootstrap of 100; Pla2g3as and Pla2g3bs of spotted gar and teleost’s excluding common carp and zebrafish fell into one branch with a bootstrap of 96; Pla2g3bs of common carp and zebrafish formed a separate branch, demonstrating a larger variation of the gene during evolution. The expression of Ccpla2g3as was generally low during the whole early developmental stages of common carp, and it was higher in liver than other detected tissues (P<0.01) in adult fish; the expression level of Ccpla2g3b at 0.5h after fertilization was significantly higher than that of the later sampling points (P<0.05) with the highest level in ovary (P<0.01); the expression of Ccpla2g3cs reached the highest level at 120h, and it was higher in brain than in other parts. Generally, this study revealed the genetic structure, phylogeny and expression patterns of sPLA2-III in common carp.
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[Abstract](308) [FullText HTML](121) [PDF 783KB](3)
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Stylonychia lemnae is a monocyte eukaryote with animal nutrition. It is also an important model protozoa to study cytology and genetics. Sterile pure culture is an important basis for the study of Stylonychia biology. In order to build a high-efficiency pure cultured system for Stylonychia, a Tetrahymena thermophila sterile pure cultured medium was referenced in this paper. And a response surface analysis was used to carried out single-factor and orthogonal experiments focused on the ratio of nitrogen source, carbon source and dipotassium hydrogen phosphate. A sterile pure cultured medium for Stylonychia was primarily established and some key cultured conditions were optimized including cultured temperature, initial pH, medium volume and initial cell density. Results showed that the securable maximum cell amount was about 3.0×103 cells and the best conditions were initial amount 100 cells, medium volume 10 mL, initial pH 7.0 and the cultured temperature 25℃
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[Abstract](327) [FullText HTML](101) [PDF 780KB](2)
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This study analyzed the effects of dissolved oxygen content (DOC) and water temperature on the community and richness of bacteria in In-pond Raceway System (IPRS) from various viewpoints using Illumina Miseq high-throughput sequencing technology. The highest and lowest microbial richness was in September and October, respectively. In general, the microbial richness in lowest DOC was greater than that in highest DOC during the diurnal variation. The microbial richness in fecal collecting area was greater than that in aquaculture area. Proteobacteria, Actinobacteria, Bacteroidetes and Cyanobacteria were the 4 dominant species among July and November. At generic levels, Pseudomonas, Synechococcus and Flarobacterium were dominant species. Almost every bacterium had significant or extremely significant difference among different months. The richness of Pseudomonas was positively correlated to DOC (r=0.415, P<0.01), but negatively correlated to water temperature (r=–0.427, P<0.01). There was a significant correlation between Synechococcus, Cyanobacteria, CL500-29, Alpinimonas and water temperature (r=0.636, –0.448, 0.755, –0.428 respectively, P<0.01). The richness of Mycobacterium (r=0.488, P<0.01) and MNG7 were significantly correlated to DOC. Furthermore, there were significant or extremely significant relations among different bacterial communities. The microbial richness increased with the decreasing DOC level to reach peak level at 2.5 mg/L of DOC. These results suggest that stocking density, culture area, DOC, and season variety could regulate microbial richness.
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[Abstract](266) [FullText HTML](128) [PDF 622KB](4)
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To investigate effects of dietary rapeseed meal on the growth performance, intestinal morphology, microflora, and the expression of small peptide transport related genes of grass carp (Ctenopharyngodon idellus), four isonitrogenous and isolipidic diets were formulated by adding 0, 5%, 10% and 15% fermented sesame meal to replace 0, 11.8%, 23.5% and 35.1% of rapeseed meal protein respectively, which were named as control group, trial group 1, trial group 2 and trial group 3. The experiment was carried out in an indoor recirculating system with three replicates in each group. Triplicates of 20 fish [initial body weight of (99.98±0.69) g] were fed to apparent satiation with four experiment diets twice a day for 45 days. The results showed no significant difference in weight gain rate (WGR), specific growth rate (SGR) and protein efficiency rate (PER) among all the groups, and WGR, SGR and PER of trial group 1 and 2 were slightly higher than those of the control group (P>0.05). Feed conversion ratio (FCR) of trial group 1 and 2 was slightly lower than that of the control group (P>0.05). The heights of intestinal villi in the trial groups were significantly higher than those of the control group (P<0.05), while the depth of crypt in the trial groups was significantly lower than that of the control group (P>0.05). The ratio of villi height to crypt depth (V/C) in the trial groups were significantly higher than that of the control group (P<0.05). Dietary fermented sesame meal significantly induced Lactobacillus and Bacillus (P<0.05) and significantly decreased Escherichia coli and Aeromonas (P<0.05). The expressions of CDX2, Sp1 and PepT1 genes increased significantly at first and then decreased with the increasing fermented sesame meal inclusion (P<0.05). These results suggest that the optimum proportion of fermented sesame meal replacement dietary rapeseed meal was 11.8%—23.5%.
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[Abstract](297) [FullText HTML](98) [PDF 503KB](1)
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To investigate the effects of different forms of dietary methionine on rice field eel (Monopterus albus) [initial weight (30±0.45) g], Crystalline methionine (C-Met), encapsulated methionine (E-Met), methionine hydroxyl analog calcium salt (MHA-Ca) and methionine hydroxy analogue (MHA), whose effective Met content was 2 g/kg, were added in basal diet to form five experimental diets for a 10-week trial. Results showed that methionine in all forms improved weight gain rate and protein efficiency ratio and decreased feed conversion rate of rice field eels with significant change in groups of MHA-Ca and MHA compared with control group (P<0.05). Methionine addition significantly improved activity of trypsin, the contents of serum bile acid, total cholesterol, total protein, urea nitrogen and ammonia, muscle gumminess and adhesiveness (P<0.05). MHA-Ca and MHA addition improved the contents of serum glucose and HDL, activity of intestinal amylase, hepatosomatic GOT, crude protein of whole fish, muscle hardness, springiness and chewiness significantly (P<0.05), but reduced hepatosomatic index and serum glutamic oxalacetic transaminase activity significantly (P<0.05). The peak level of serum methionine appeared at 6h in control group after feeding, but at 9h in C-Met and MHA-Ca groups, at 12h in E-Met group, and at 3h and 9h in MHA group. These results revealed that methionine addition improved growth performance of rice field eels with better effects for MHA-Ca and MHA.
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[Abstract](320) [FullText HTML](134) [PDF 934KB](8)
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To evaluate the water quality situation, this study investigated zooplankton species, density and biomass and the main water quality indexes like water temperature, conductivity, DO and pH in 12 cross-sections in the Wei River Basin in October of 2017 and June of 2018, respectively, using the biological diversity index method. 57 species of zooplankton species (11 species of protozoa, 33 species of rotifers, 7 species of cladocerans, 6 species of copepods) were identified, and the dominant species was Brachionus calyciflorus. During dry season, the density of zooplankton varied between 0.72—7.84 ind./L with the average density of (2.79±2.11) ind./L, and the biomass ranged 0.38[6.15 mg/L with the average biomass of (2.31±2.64) mg/L. The diversity indices of Shannon-Wiener and Margalef were 1.07 and 0.69, respectively. The canonical correspondence analysis indicated that the community structure of zooplankton in the Wei River Basin was primarily affected by the water environment including temperature, DO, altitude and conductivity. During wet season, the density of zooplankton varied between 0–179.02 ind./L with an average density of (16.66±49.18) ind./L, and the biomass ranged 0–2448.12 mg/L with an average biomass of (243.96±673.78) mg/L. The diversity indices of Shannon-Wiener and Margalef were 0.78 and 1.15, respectivly. The water quality of Wei River in Beidao and Linjiacun was moderately polluted, and the water qualities in Weijiabao were heavy pollution, and in Xianyang, Lintong, Huaxian the water qualities were light pollution. The water quality of Jing River in Yangjiaping, Yuluoping and Zhangjiashan was moderately polluted. The water quality of Beiluo River in Liujiahe, Jiaokouhe and Zhuangtou was moderately polluted.
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[Abstract](344) [FullText HTML](141) [PDF 1252KB](5)
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This study investigated growth performance and hypoxia tolerant ability of the yellow catfish and the hybrid catfish called " Huangyou No. 1” for an 8-week trial. The results showed that the average weight of the hybrid catfish was (19.60±0.88) g/tail at week 8, which was significantly higher than that of the yellow catfish was (15.74±0.42) g/tail (P<0.05) with a 24.52% increase. The feed coefficient of the hybrid catfish and the yellow catfish were 1.18±0.14 and 1.36±0.21, respectively. The survival rate of young hybrids catfish was 87.78±1.92, which was significantly higher than that of the yellow catfish at 67.78±1.92 (P<0.05). The survival rate of the hybrid catfish was 29.51% higher than that of the yellow catfish. The hybrid catfish and yellow catfish were placed in water with dissolved oxygen content of (1.48±0.27)mg/L and then hypoxia stress for 0, 6, 12 and 24h before collecting serum and liver for measurements. Hypoxia stress significantly regulated the LDH activity, SOD activity, CAT activity at 6h and the T-AOC at 12h in the serum and liver of both hybrid catfish and yellow catfish (P<0.05). The brain and liver HIF-1α mRNA level of both hybrid catfish and yellow catfish increased significantly by hypoxic stress (P<0.05) with higher level in hybrid catfish at 6, 12 and 24h. These results indicated that long-term hypoxic stress may cause oxidative damage to hybrid catfish and yellow catfish, but hypoxia tolerance of hybrid catfish is higher than that of yellow catfish.
Available online   , doi: 10.7541/2019.128
[Abstract](26) [PDF 795KB](2)
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This study re-described Myxobolus wulii (Wu & Li) Landsberg & Lom, 1991 and compared its strains in different sections of Yangtze River Basin (Chongqing strain, Hubei strain and Jiangsu strain) based on morphological and molecular (18S rDNA) data. The results showed that the spores and polar capsules of Chongqing strain were slightly smaller than those of Hubei strain, and that polar capsules and spores of Chongqing strain were equal in size while they were unequal for Hubei strain. The similarities and genetic distances among the three strains of M. wulii were 99.2%—99.9% and 0.002—0.007, respectively. Phylogenetic analysis showed that the sequences of M. wulii formed a poor geographical structure as well as poor host-original structure, but a strong parasitic site structure. The sequences of M. wulii clustered into two lineages: gill-parasites clade and hepatopancreas-parasites clade, indicating that the individuals of M. wulii have closer relationship with the same site of host. Moreover, the gill-parasites clade diverged earlier than hepatopancreas-parasites clade, which might be related to the evolution of external-parasites to internal-parasites. These data inferred that the gill-parasites population might be the earliest migrates of M. wulii.
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[Abstract](396) [FullText HTML](231) [PDF 634KB](12)
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Habitat quality can directly affect population abundance and distribution of the Yangtze finless porpoise. This study investigated habitat status of both south and north banks of the main stem of the Yangtze River by taking high-resolution digital photos systematically during the 2017 Yangtze Freshwater Dolphin Expedition from November 10th to December 17th, 2017. The survey area covered the entire middle and lower reaches of the Yangtze River from Yichang to Shanghai (1669 km in length) and a total of 794 photo samples were collected. We recorded 318 sightings with 631 individuals of the Yangtze finless porpoise. The Chi-squared goodness of fit test revealed that proportions of observed frequency are significantly higher than the expected frequency in natural river banks (χ2=69.81, P<0.001). Whereas the result is opposite in the semi-natural and solidified river banks (χ2=39.26, P<0.001; χ2=12.15, P<0.001), indicating that the natural river banks were the preferred habitat of the Yangtze finless porpoise. The length of the semi-natural river and solidified banks accounted for 45.47% of the total length of the river bank, which intermingled with the patches of the natural river banks, demonstrating that the natural habitat was severely degraded and highly fragmented to impact the distribution of the Yangtze finless porpoise. Our study suggested that habitat degradation and fragmentation pose a significant threat to the survival of the Yangtze finless porpoise. Future conservation research and practice should focus on habitat restoration of the solidified river banks to reestablish and enhance habitat connectivity.
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[Abstract](398) [FullText HTML](165) [PDF 951KB](0)
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In order to prove up the spatial distribution patterns of Sgassum vachellianum in Northern Zhejiang nearshore typical reefs, investigations were conducted on three reef belts with 12 reefs from the end of May to the beginning of June, 2016. Researchers carried out vessel-mounted observations and collected samples with SCUBA (Self-Contained Underwater Breathing Apparatus) to find out and compare the differentia of horizontal and vertical distribution features of S. vachellianum in adult stages. The results showed that (1) at the area scale, water environment with high turbidity and high wave energy inhibited the growth and spread of S. vachellianum which could merely be found on the second narrow reef belt. According to the growth characteristics of minimum appropriate water temperature with 10 ℃, it can be inferred that the northernmost island of Zhoushan Archipelago is the northernmost spread limit of endemic S. vachellianum to China. (2) At the site scale, the factor of wave exposure might explain the reason why S. vachellianum were sparse in southeast and were rich in northwest of reefs. The average height of S. vachellianum was only 26.3 cm on the four reefs of the second reef belt, which indicates high wave energy is not suitable for its growth. (3) Within the site scale, the North Yushan Island on the second reef belt was with lowest turbidity so that S. vachellianum were widespread, which could even be found in depth of 6.4 m. However, coastal waters with high turbidity withheld vertical distribution of S. vachellianum. As the result showed the average height of S. vachellianum decreases with depth, which can be inferred that S. vachellianum were intolerance of intense light, but light is a major factor for its distribution. Compared with the vertical distribution of Sargassum horneri in this region, S. vachellianum were adaptive to the environment with high turbidity and high sediment. Therefore, the change of inhibited water environment has driven S. vachellianum to the edge of extinction. By studying the causes of the spatial distribution of S. vachellianum, the decline of algae fields and the trend of variation, the conclusion can be drawn that S. vachellianum are suitable for artificial transplantation in Northern Zhejiang coastal area. The findings can provide meaningful references for the protection and restoration of algae fields.
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[Abstract](397) [PDF 930KB](1)
Abstract:
To investigate the effects of enzymatic hydrolyzed soybean meal(ESBM)on growth performance, liver function and metabolism of largemouth bass (Micropterus salmoides), five isonitrogenous and isoenergetic diets were formulated by replacing fish meal with a plant-based protein source compound (enzymatic hydrolyzed soybean meal: corn gluten meal=10 鲶1) for a 67-days trial. The additions of ESBM in the feed were 0 (E0), 15% (E15), 20% (E20), 25% (E25), 30% (E30) to replace 0, 23.64%, 30.91%, 40%, 47.27% of the fish meal, respectively. In additional, two diets of soybean meal (SBM) and fermented soybean meal (FSBM) were used as the substitute for 20% ESBM, respectively. The results showed that the specific growth rate and weight gain rate of E25 and E30 were significantly higher than those of other groups (P<0.05), and that the feed coefficient ratio of each group had no significant difference (P>0.05). The survival rates of the E25 and E30 groups were lower than other groups. With the increase of ESBM, the viscerosomatic index, hepatic index and the lipid content of body decreased significantly (P<0.05). The specific growth rate of FSBM group was significantly lower than that of E20 group (P<0.05), and viscerosomatic index and hepatic index of FBSM were significantly higher than those of SBM and E20 (P<0.05). The activities of amylase and lipase of intestines increased first and then decreased with the increased ESBM, which were significantly higher than that of the control group (P<0.05). The activity of pepsin in E20 and E30 group was significantly higher than control group (P<0.05). The activity of amylase in FSBM group was significantly higher than SBM and E20 (P<0.05), while the change of intestinal lipase activity was opposite. The activities of liver total-antioxidant capacity (T-AOC), glutamic oxaloacetic transaminase (AST) and alanine aminotransferase (ALT) in all group except liver ALT in E30 group were significantly induced by ESBM (P<0.05), and ESBM significantly reduced liver malondialdehyde (MDA) (P<0.05). The liver MDA content and ALT activities of FSBM group was significantly lower than SBM and E20 group (P<0.05), and the liver AST activity was in the order of E20>FSBM>SBM. The oxygen consumption increased significantly with the increased ESBM, and the nitrogen excretion in E20, E25 and E30 were significantly higher than E0 group (P<0.05). The muscle nitrogen retention rates of E20 and E30 were higher than other groups. ESBM had significant effects on serum free fatty acid (NEFA), total cholesterol (T-CHO), triglyceride (TG), and low density lipoprotein cholesterol (LDL-C) of largemouth bass. Among E20, FSBM and SBM groups, the oxygen consumption in FSBM group was significantly lower than other two groups (P<0.05), while nitrogen excretion was opposite. The serum T-CHO of SBM group was significantly higher than other two groups (P<0.05), while serum LDL-C and muscle lipid were the contrary trend. The serum TG of E20 group was significantly lower than other two groups (P<0.05). These results indicate that the addition of ESBM up to 30% did not harm the growth, and reduced liver oxidative stress to enhance nutrients metabolism. ALL FSBM, SBM and ESBM have benefits to replace 30.91% fish meal with the best effects by ESBM.
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[Abstract](328) [PDF 930KB](0)
Abstract:
To investigate the effects of enzymatic hydrolyzed soybean meal(ESBM)on growth performance, liver function and metabolism of largemouth bass (Micropterus salmoides), five isonitrogenous and isoenergetic diets were formulated by replacing fish meal with a plant-based protein source compound (enzymatic hydrolyzed soybean meal: corn gluten meal=10 鲶1) for a 67-days trial. The additions of ESBM in the feed were 0 (E0), 15% (E15), 20% (E20), 25% (E25), 30% (E30) to replace 0, 23.64%, 30.91%, 40%, 47.27% of the fish meal, respectively. In additional, two diets of soybean meal (SBM) and fermented soybean meal (FSBM) were used as the substitute for 20% ESBM, respectively. The results showed that the specific growth rate and weight gain rate of E25 and E30 were significantly higher than those of other groups (P<0.05), and that the feed coefficient ratio of each group had no significant difference (P>0.05). The survival rates of the E25 and E30 groups were lower than other groups. With the increase of ESBM, the viscerosomatic index, hepatic index and the lipid content of body decreased significantly (P<0.05). The specific growth rate of FSBM group was significantly lower than that of E20 group (P<0.05), and viscerosomatic index and hepatic index of FBSM were significantly higher than those of SBM and E20 (P<0.05). The activities of amylase and lipase of intestines increased first and then decreased with the increased ESBM, which were significantly higher than that of the control group (P<0.05). The activity of pepsin in E20 and E30 group was significantly higher than control group (P<0.05). The activity of amylase in FSBM group was significantly higher than SBM and E20 (P<0.05), while the change of intestinal lipase activity was opposite. The activities of liver total-antioxidant capacity (T-AOC), glutamic oxaloacetic transaminase (AST) and alanine aminotransferase (ALT) in all group except liver ALT in E30 group were significantly induced by ESBM (P<0.05), and ESBM significantly reduced liver malondialdehyde (MDA) (P<0.05). The liver MDA content and ALT activities of FSBM group was significantly lower than SBM and E20 group (P<0.05), and the liver AST activity was in the order of E20>FSBM>SBM. The oxygen consumption increased significantly with the increased ESBM, and the nitrogen excretion in E20, E25 and E30 were significantly higher than E0 group (P<0.05). The muscle nitrogen retention rates of E20 and E30 were higher than other groups. ESBM had significant effects on serum free fatty acid (NEFA), total cholesterol (T-CHO), triglyceride (TG), and low density lipoprotein cholesterol (LDL-C) of largemouth bass. Among E20, FSBM and SBM groups, the oxygen consumption in FSBM group was significantly lower than other two groups (P<0.05), while nitrogen excretion was opposite. The serum T-CHO of SBM group was significantly higher than other two groups (P<0.05), while serum LDL-C and muscle lipid were the contrary trend. The serum TG of E20 group was significantly lower than other two groups (P<0.05). These results indicate that the addition of ESBM up to 30% did not harm the growth, and reduced liver oxidative stress to enhance nutrients metabolism. ALL FSBM, SBM and ESBM have benefits to replace 30.91% fish meal with the best effects by ESBM.
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[Abstract](362) [FullText HTML](210) [PDF 490KB](3)
Abstract:
We generally reviewed the distributions and potential risks of heavy metals, polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in the upper reaches of the Yangtze River based on recent studies. The distribution of heavy metals varied significantly with locations and types of mediums, and contents of some metals exceeded the limits in food. The contents of PAHs in the upper reaches of the Yangtze River were in line with those in the lower reaches. Low molecular weight PAHs were predominant in surface water, while high molecular weight PAHs were predominant in sediments, indicating low molecular PAHs may pose greater risks to aquatic ecosystems. DEHP and DBP were the predominant monomers of PAEs in surface water and sediments, and BBP and DBP ranked first and second respectively in fish bodies. The results of risk assessment also indicated that monomers such as DBP and DnBP had greater risk than DEHP. Over all, heavy metals and organic pollutants were widely distributed in the aquatic environment in the upper reaches of the Yangtze River, which may pose potential risks to the ecosystem.
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[Abstract](387) [FullText HTML](237) [PDF 690KB](19)
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The Chishui River, the only undammed first-order tributary of the upper Yangtze River Basin, is an important part of the " National Nature Reserve for Rare and Endemic Fishes of the Upper Yangtze River”, which plays important roles in fish conservation. To determine main environmental factors that affect the breeding activities of fishes with drifting eggs in this river, investigations on fish resources of early life stages were carried out in Chishui Reach from March to July in 2015 and April to August in 2016. A total of 27 species of fish early resources, belonging to 3 orders, 7 families and 22 genera, were collected during the investigation period. Nine of these species including Pseudolaubuca engraulis, Squalidus argentatus, Gobiobotia filifer, Botia superciliaris, Parabotia fasciata, Parabotia bimaculata, Leptobotia elongate, Leptobotia taeniops and Lepturichthys fimbriata laid drifting eggs in the running water. Canonical Correspondence Analysis (CCA) revealed various breeding environmental requirements for these species. Specially, B. superciliari, P. fasciata, P. bimaculata, L. elongate, L. taeniops and L. fimbriata tended to lay eggs when the water discharge was increasing, while P. engraulis and S. argentatus showed an opposite trend. Additionally, G. filifer preformed differently between 2015 and 2016. In the low flow year, their reproductive activities were positively associated with the water discharge. However, in the high flow year, no significant relation between the reproduction activities and water discharge was observed. These results strengthen our understanding of reproductive behavior of different fish species and provide valuable insights into fish conservation.
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[Abstract](411) [FullText HTML](175) [PDF 735KB](5)
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Eco-hydrological regulation of lakes have received more and more attentions in recent years, but systemic research on hydrological requirements of aquatic organisms still is limited. We systematically summarized the current status of aquatic plants and water level in the mid-lower Yangtze shallow lakes, influences of water level fluctuations on aquatic plants, and the requirement mode of water level fluctuation of aquatic plants. We also introduced a new method assessing ecological water level in shallow lakes based on aquatic plants, and provided corresponding strategies of water level regulations for lakes with different functions.
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[Abstract](442) [FullText HTML](247) [PDF 569KB](30)
Abstract:
Sinogastromyzon sichangensis is a small-size fish endemic to the upper Yangtze River mainly distributed in main stream and tributaries. Twenty-nine polymorphic microsatellite loci of the S. sichangensis were isolated by next-generation sequencing techniques. Four wild populations in Chishui River were amplified by 20 loci with mean alleles 14.5. The mean observed (Ho) and expected (He) heterozygosity were 0.620 and 0.882, respectively and the mean polymorphic information content (PIC) was 0.859. The Ho ranged from 0.520 (Maotai Town) to 0.669 (Chishui Town) and PIC ranged from 0.841 (Maotai Town) to 0.868 (Xishui River). The Fst value and analysis of population structure revealed a genetic differentiation between populations from Xishui River and the main stream of Chishui River. AMOVA showed that the genetic variation was 3.33% among populations while it was 96.67% within populations. These novel loci could use to investigate the population genetics and biological resource conservation strategy in S. sichangensis.
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[Abstract](575) [FullText HTML](266) [PDF 23157KB](49)
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We compiled the distribution and traits of 214 fish species and subspecies in the Jinsha River basin to investigate systematic and effective conservation planning in the basin. First, we modelled the distribution of widespread species throughout the basin with environmental factors such as climate, riverscape, land-use, and soil type; we used the occurrences as the distribution for other species. We planned the protected area (PA) network with the Marxan software to determine the species-specific conservation targets (grouped by mobility, distribution range, and conservation status) and evaluate the protection status of the current wetlands PAs. The best solution selected 486 planning units (47950 km2) that was 7.7% of the total planning units. The current wetlands PAs was not enough for fish conservation, which shelters 59.3% of all fishes (127 species) and 109 species require additional conservation area. The planning units’ area protected by the wetlands PA need to expand 55.9% to reach our conservation target.
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[Abstract](667) [FullText HTML](319) [PDF 818KB](68)
Abstract:
The Yangtze River basin harbors a high degree of fish diversity, with 378 fish species distributing in the mainstream and its attached waters, and 149 of these species are endemic to this river. Meanwhile, the Yangtze River is an important fishery ground in China, contributing more than 60% of the total catch of freshwater fishery. Therefore, the Yangtze River plays important roles in both biodiversity conservation and capture fisheries. However, due to the increasing human activities in the past decades, fish resources in the Yangtze River have declined sharply. Firstly, more and more species have been assessed as threatened and the endangerment categories of many species have been upgraded. Secondly, the population size of many iconic species, such as Acipenser sinensis, the four famous Chinese carps and Coreius guichenoti, have declined continuously. Thirdly, the miniaturization tendencies of major fishing targets have become more and more obvious. Last but not the least, the total fishery catch reduced significantly. Overfishing, water projects construction, enclosing-lake cultivation, water pollution and alien invasion were the main reasons contributing to these changes. In most situations, these factors interacted together, which imposed more damage to the fish resources and increased the difficulty of conservation. In order to protect the fish resources in the Yangtze River effectively, following conservation strategies are suggested: establishing specialized nature reserve, banning commercial fishing completely, implementing river ecological restoration, strengthening scientific research and establishing comprehensive regulation mechanism.
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[Abstract](495) [FullText HTML](159) [PDF 696KB](12)
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Based on the Gini coefficient and Mann-Kendall test, the runoff variation in the Yichang reach of Yangtze River from 1982 to 2017 was evaluated, and its influence to the Chinese sturgeon spawning below the Gezhouba Dam was discussed under the cascaded hydropower operation. The results showed that the runoff and Gini coefficient decreased significantly after the construction of Gezhouba Dam, which synchronously decreased the flow and water levels in spawning days of the Chinese sturgeon. Water temperature had no significant change. The analysis of the abruption revealed great change of hydrological conditions in the spawning days and Gini coefficient in 2004 and 2009, which are coincided with time of the second and fourth phase impoundment of the Three Gorges Reservoir. The correlation analysis indicated that the higher runoff and Gini coefficient would induce Chinese sturgeon to spawn in days with high flow and water levels. These results suggest that the ecological operation of the Three Gorges-Gezhouba cascaded hydropower could enhance the runoff with large inequality and create long duration of high flow pulses during flood seasons.
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[Abstract](364) [FullText HTML](218) [PDF 599KB](18)
Abstract:
Lake Dongting is the second largest floodplain lake along the Yangtze River basin. However, the study on fish communities in the Dongting Lake is limited, lacking systematic research on the spatio-temporal variations of fish assemblages in this area. Fish were sampled seasonally from December 2012 to October 2014 in the Dongting Lake. 80 fish species belonging to54 genera, 17 families, and 7 orders with dominant Cyprinidae accounting for 58.8% of the total species were collected. The species richness reduced by 36 in contrast with the historic records. The number and percentage of riverine and river-sea migratory species decreased by 13 (2.2%) and 4 (3.0%) respectively in comparison with historic records. We detected significant seasonal and regional differences in species composition and biodiversity. The diversity and evenness of fishes were significantly higher in summer and autumn than those in other seasons. Meanwhile, significantly lower diversity was observed in the east Dongting Lake than other regions. Our results indicated that seasonal flood pulses and, assisting by river-lake connectivity may play a fundamental role for the fish resources supplement in floodplain lakes. This study demonstrated significant spatio-temporal variations of fish assemblages in the Dongting Lake, which provided scientific foundations for fish conservation in this area.
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[Abstract](969) [FullText HTML](499) [PDF 760KB](74)
Abstract:
Three Gorges Reservoir (TGR) is the key project for the governance and development of the Yangtze River. TGR is an important region for the ecological and environmental protection in the Yangtze River economic belt. The hydrology and water environment have taken fundamental changes since the impoundment of TGR with some negative ecological and environmental problems. To address whether the aquatic ecosystem of TGR is healthy or not, the phytoplankton community index (PhyCoI) was used to assess the ecosystem health of TGR. Field survey was carried out on April 2015 in the whole region of TGR, including 23 tributary bays and 18 sections in the main channel of TGR with 174 sampling sites. A total of 61 phytoplankton taxa were identified, belonging to Cyanophyta, Chlorophyta, Bacillariophyta, Cryptophyta, Pyrrophyta, Euglenophyta, and Chrysophyta. Based on the scores of PhyCoI, the overall health status of TGR is good, with 68% sites in the status of very healthy (4≤PhyCoI<5) or healthy (3≤PhyCoI<4), 26% sites in sub-healthy (2≤PhyCoI<3), and 6% sites in general sick condition (1≤PhyCoI<2). Specifically, 96% sites in the main channel of TGR are healthy, and other 4% sites are in the status of sub-healthy. In the tributary bays, the ratios for the status of very healthy, healthy, sub-healthy, and general sick are 2%, 53%, 35%, and 9%, respectively. From the view of spatial distribution, overall health status of the main channel of TGR is good, and the health status of the main channel in Hubei Province is better than that in the Chongqing Province. In addition, the health status of sites in the Xiangxi Bay, Meixi Bay, and Xiaojiang Bay were highly variable. And in general, the health status of the bays near the dam of TGR is better than the bays far away from the dam. These results provide science and technology support for ecological and environmental protection of TGR.
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[Abstract](869) [FullText HTML](498) [PDF 1077KB](77)
Abstract:
The Yangtze River is the largest river in China. It is a priority conservation area for biodiversity of the world, with its main river, branches and wetlands. As an essential part of freshwater ecosystem, aquatic vegetation has been well studied by Chinese researchers since 1950s, but large-scaled analysis on the biodiversity pattern is lacked. Based on published studies, we analyzed spatial and temporal pattern of aquatic plant diversity in the Yangtze River Basin, and calculated the suitable habitat area and underlying influence of environmental factors using MaxEnt software. A total of 298 species are recognized, belonging to 121 genera in 52 families, which is 57.6% of the total aquatic vascular plants in China. The Yangtze River Basin is the key area for aquatic plant diversity of China, especially the subregions of middle reaches. The elevation and land use are the key environmental variables to the spatial pattern of aquatic plants. The separation among water systems have weak influence on the spatial pattern of diversity in aquatic vascular plants, but potamo-lacustrine habitats facilitated the species homogenization of the flora in a sub-basin scale. The network consists of Poyang Lake, Dongting Lake, Tai Lake, and the middle and lower mainstream is the suitable area for the aquatic plants based on the MaxEnt model. In the past half century, the decline or loss of aquatic vegetation occurred in plenty of lakes in the Yangtze River Basin. We suggested that the protection of aquatic vegetation should be incorporated into the integrated conservation of the middle and lower Yangtze River.
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[Abstract](718) [FullText HTML](450) [PDF 681KB](17)
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PAEs have been proved to be one of the major organic pollutants. The present study determined the level of PAEs using surface water samples from the upper reaches of the Yangtze River. The results showed that DEHP contributed the most to PAEs pollution, followed by DBP. Risk Quotients of PAEs were used for preliminary screening, and DEHP and BBP were identified as potential risk factors with RQ of 310 and 70.7. The MOS10 of DEHP and BBP were 1.40 and 1.32×105, respectively, indicating that BBP may pose little risk to aquatic organisms. The potential risk of DEHP was further analyzed with joint probabilistic curves. Among different biological groups, fish and zoobenthos were two major groups sensitive to DEHP-induced damage under current concentrations with 99.4% and 98.3% for 5% species of each group. While among the toxicity endpoints, reproduction may be more sensitive than others. The 5% and 10% aquatic species were suffered from reproductive damages by 100% and 97.8%, respectively. Overall, our results indicated that DEHP in the surface water of the upper Yangtze River may pose potential risk to aquatic organisms, especially on their reproduction. Therefore, more concerns should be paid in species protection and environmental management.
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[Abstract](629) [FullText HTML](390) [PDF 766KB](49)
Abstract:
To better understand zooplankton distribution and its relationship with the physical-chemical factors in middle Yangtze River, we collected 20 zooplankton samples from segments at Yichang, Jingzhou, Yueyang, Wuhan and Hukou in October, 2016. A total of 23 species that belong to 13 families and 14 genera were identified, among which 16 species belong to Rotifera, 4 to Copepoda and 3 to Cladocera. Among the five segments, the highest number of zooplankton species was detected at Hukou (9 species), while the lowest was at Yueyang (5 species). The average density at Wuhan (10.94±5.81) ind./L was higher than that at Hukou and the other segments. Rotifers (3.41±0.21) ind./L were dominant in the zooplanktonic community, and Keratella valga, Synchacta atylata and Keratella cochlearis were the dominant species. The average density of copepods (mainly nauplius) was (0.75±0.07) ind./L. Cladocera had the lowest average density. Similarly, the zooplankton biomass at Wuhan was also higher than that at Hukou and the other three segments. Comparing with studies at other segments of Yangtze River, we detected lower zooplankton diversity in our investigation. Spearman correlations indicated that the biomass and diversity of zooplankton were significantly and positively correlated (P<0.05) to chlorophyll a.
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[Abstract](603) [FullText HTML](376) [PDF 507KB](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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2019, 43(5): 923 -930   doi: 10.7541/2019.109
[Abstract](737) [FullText HTML](240) [PDF 624KB](108)
Abstract:
The Yarlung Zangbo River (the upper Brahmaputa River) is the largest river on the Tibetan Plateau. The present study investigated the genetic diversity and population demography of Schizothorax molesworthi from the Motuo area of lower reaches of the Yarlung Zangbo River and Lohit River using mitochondrial DNA Cyt b gene sequences. The results showed that 21 haplotypes were identified for 167 individuals with relatively high haplotype diversity (h= 0.768) and low nucleotide diversity (π=0.00167). Phylogenetic trees and Network diagram based on haplotypes indicated all haplotypes from the lower reaches of the Yarlung Zangbo River and Lohit River were not clustered separately but mixed with each other according to the geographical distribution. Pairwise comparisons of genetic diffe-rentiation index (FST) among different populations ranged from –0.014 to 0.771 with highly significant genetic differentiations between the JZZB population and other populations (FST: 0.372—0.771). The analysis of molecular variance (AMOVA) showed that the largest mean FCT index was found between JZZB population and the group of other six populations. Neutral test, mismatch analysis and BSP (Bayesian skyline plot) analysis showed that overall S. molesworthi population from the lower reaches of the Yarlung Zangbo River and Lohit River experienced population expansion during the last glaciations BP (0—0.137 Ma).
2019, 43(5): 931 -938   doi: 10.7541/2019.110
[Abstract](555) [FullText HTML](144) [PDF 726KB](60)
Abstract:
Natural resources of Barbatula toni have been seriously damaged in recent years due to habitat destruction and overfishing, which need urgent protection. The present study used mitochondrial DNA Cyt b and D-loop genes as molecular maker to perform the genetic diversity and phylogeographic analyses of three populations of B. toni from north China. 57 haplotypes were identified for 119 individuals of B. toni. No haplotype shared among different populations. Relatively high haplotype diversity (h=0.805—0.926) and low nucleotide diversity (π=0.00095—0.00458) were detected in three populations of B. toni. Haplotype Bayesian tree showed that B. toni from three river systems were separa-tely clustered as three clades. Analysis of molecular variance (AMOVA) indicated that the variation among populations (accounting for 79.45%) was the main source of variation. Differentiation index (FST) of three populations showed significant difference with FST >0.25 (P<0.01). Neutrality tests and mismatch distribution indicated the recent demographic expansion of B. toni. According to the average evolution rate of Cyt b of Cobitis melanoleuca from Siberia (0.68—0.84%/Ma), the divergence time of three populations of B. toni was 1.082—0.669 Ma, and recent demographic expansions time was at 0.071—0.047 Ma. Pleistocene climatic changes could be a key factor of the population dyna-mics.
2019, 43(5): 939 -944   doi: 10.7541/2019.111
[Abstract](557) [FullText HTML](223) [PDF 446KB](49)
Abstract:
Black carp Mylopharyngodon piceus, the most important freshwater fish in China, is widely distributed in the Yangtze River and along the Yangtze River. This study developed 12 highly polymorphic loci from 25 polymorphic microsatellite markers to analyze genetic diversity and population structure of 4 wild and 1 aquaculture populations in the Yangtze River system. The results showed that the polymorphic information content (PIC) of these 12 loci was between 0.660—0.923, indicating that all 12 loci were highly polymorphic (PIC>0.5). The allele number (Na) of the 5 populations was between 7.917—11.667 and the effective allele number (Ne) ranged from 4.837 to 6.035. The observed heterozygosity was between 0.713—0.861 and the expected heterozygosity was between 0.749—0.819. The ave-rage polymorphism information content was between 0.711—0.788. These results indicated the high genetic diversity in all 5 populations. The genetic distance between the 4 wild populations was relatively closer. The genetic distance between the cultured population and the 4 wild populations was much larger than that of the 4 wild populations. In the UPGMA phylogenetic tree, the Xiangjiang population and the Shishou population were first gathered together, and then clustered with the Hanjiang and Jiaxing populations, and finally together with the Wujiang culture population. The 12 microsatellite loci can be used for the assessment of germplasm resources and genetic diversity of different populations in black carp.
2019, 43(5): 945 -952   doi: 10.7541/2019.112
[Abstract](371) [FullText HTML](108) [PDF 785KB](44)
Abstract:
To explore genetic structure of 164 Bombay duck (Harpadon nehereus), fishes from Qingdao, Nantong, Zhoushan, Sanmen, Ningde, Quanzhou and Zhanjiang in the coastal areas of the Yellow Sea, East China Sea and South China Sea were collected to sequence the mitochondrial DNA cytochrome b (Cyt b) gene fragment. Thirty-two mutation sites, including 27 single mutation sites and 1 simple mutation site were detected. The 164 sequences defined a total of 29 haplotypes. The average haplotype diversity (Hd) and nucleotide diversity (π) were (0.3026±0.0479) and (0.000371±0.000379), respectively, and both the lowest haplotype diversity and the lowest nucleotide diversity were Quanzhou population. The average genetic distance among different populations was 0.00035 and the genetic differentiation index FST value was less than 0.05, indicating no obvious genetic differentiation among the populations. The re-sults of AMOVA showed that the genetic difference of Bombay duck populations was mainly from the variation among individuals within the population. The values of Tajima’s D and Fu’s Fs tests were both negatively and significantly deviated from neutral test. The nucleotide mismatch distribution showed distinct unimodal, indicating that Bombay duck experienced a population expansion event in history. We estimated that the population expansion occurred about 0.08—0.32 million years ago in the middle and late Quaternary Pleistocene based on the evolutionary rate of Cyt b gene 2%/Ma (millions years) in marine fishes.
2019, 43(5): 953 -961   doi: 10.7541/2019.113
[Abstract](611) [FullText HTML](210) [PDF 1267KB](48)
Abstract:
Greb1 (Growth regulation by estrogen in breast cancer cell 1), an estrogen stimulated gene, plays critical roles in estrogen response. Previous study indicated that Greb1 was highly expressed in gibel carp (Carassius gibelio) pituitary. The current study cloned and characterized the expression of Carassius gibelio Greb1 (CgGreb1), and investi-gated its function in early embryonic development. The full length cDNA of CgGreb1 was 954 bp, encoding a deduced protein of 255 amino acids. Based on the NCBI database, most vertebrates contained at least one Greb1 isoforms, whose amino acid length ranged from 386—1988 and contained conserved N-terminus. Among those Greb1 homologues, CgGreb1 was the shortest one, locating in the N-terminus of other Greb1 homologues and sharing high identi-ties over 60%. CgGreb1 was dominantly expressed in pituitary, brains, liver and gonads with the highest level in pitui-tary. The expression of CgGreb1 was gradually increased by inducing spawning gibel carp females, peaked at 6 hours post induction, and then decreased and maintained at a relatively high level. During embryogenesis, the expression of CgGreb1 started from 50% epiboly, increased as embryogenesis progression, peaked at 24 hours post fertilization (hpf), and then gradually decreased and was undetectable at 48 hpf. WISH analysis showed that CgGreb1 signal was specifi-cally located in the embryonic margin during gastrulation, gradually distributed in the central neural system during somitogenesis, and was strongly expressed in many brain regions and notochord, but was gradually weakened from 30 hpf and was disappeared at 48 hpf. Knockdown of CgGreb1 specifically decreased the expression of tshβ, prl and gthα but not pomca in producing cells, suggesting that CgGreb1 played an important role in early pituitary development in gibel carp. Our present study provides insights into the molecular mechanism underlying pituitary development and growth regulation in gibel carp.
2019, 43(5): 962 -968   doi: 10.7541/2019.114
[Abstract](444) [FullText HTML](201) [PDF 418KB](29)
Abstract:
Growth traits are controlled by multiple genes to cause minor phenotypic effect. To understand the pyra-miding effect of advantage genotypes of growth-related molecular markers in largemouth bass (Micropterus salmoides), thirteen molecular markers related to growth traits were selected obtained on previous studies, which were loca-ted in PCK1, HSBP1, FOXO3b, MYH, HSC70-1, CTSB, HBP, POU1F1, PACAP, IGF-I, ghrelin, ApoproteinA and MSTN. The genotype of each marker in forty largemouth bass parents was analyzed and 2 families were constructed basing on pyramiding advantage genotypes. 305 and 266 individuals were sampled randomly from second filial generation of two families at nine month old, respectively. The results showed that the number of advantage genotypes was various in all offspring of family 1 with the number of individuals of each group 8, 26, 75, 74, 76, 35 and 11, respecti-vely. The average weight of advantage genotypes group was 185.03, 196.46, 198.73, 212.59, 222.66, 235.54 and 261.27 g, respectively. In the offspring of family 2, the number of advantage genotype ranged from one to six with the average weight of 184.43, 213.17, 243.77, 249.98, 252.11 and 266.00 g, respectively. Correlation analysis showed that the pyramiding number of advantage genotype was correlated with growth traits. Our results present evidence to improve the growth trait of largemouth bass by utilizing the limited advantage genotypes. This study provided scientific basis for the application of molecular marker assisted breeding in largemouth bass.
2019, 43(5): 969 -976   doi: 10.7541/2019.115
[Abstract](427) [FullText HTML](213) [PDF 1470KB](18)
Abstract:
To investigate the effect of temperature on transcripts and relative mRNA levels, high-throughput RNA sequencing were used for Yersinia ruckeri grown at 28℃ and 37℃. After the quality control, all differentially regulated genes were enriched and annotated by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and verified by Rockhopper software. The results showed that 173 differentially expressed genes were identified (P-value<0.05), including 58 up-regulated genes mainly enriched in several KEGG pathways: phosphotransferase system, starch and sucrose metabolism, galactose metabolism and other glycan degradation; and 115 down-regulated genes mainly enriched in several KEGG pathways: two-component system, thiamine metabolism and flagellar assembly. In summary, the SC09 had lower motility and weaker glucose metabolism at temperature of 37℃. The compensatory overexpression of some specific carbohydrate metabolism might play important roles for the survival of this bacterial under high temperature. This study provides an important basis for further research on the molecular mechanisms of SC09 in different temperatures.
2019, 43(5): 977 -982   doi: 10.7541/2019.116
[Abstract](411) [FullText HTML](128) [PDF 690KB](8)
Abstract:
In this study, open reading frame (ORF) of glycoprotein (1530 bp) was amplified by using RNA extracted from Spring Virernia of Carp Virus (SVCV). The SVCV G ORF was cloned into pYD1 vector to construct a recombi-nant plasmid pYD1-G and then transformed into competent yeast cells EBY100, and positive colonies were screened by colony PCR. The expression of G gene was induced by 2% glucose and detected by cell immunofluorescence and flow cytometry. The immunofluorescence staining observed increased EBY100-pYD1-G signal of induced yeast cells with increased induction time. Flow cytometry analysis observed significantly increased fluorescence intensities in prolonged induced EBY100-pYD1-G cells (P<0.05). These results indicated the SVCV G protein has been successfully expressed and localized on the surface of yeast cell. This study laid a foundation for the novel oral vaccine development against SVCV infection in carps in future.
2019, 43(5): 983 -991   doi: 10.7541/2019.117
[Abstract](422) [FullText HTML](182) [PDF 1692KB](15)
Abstract:
To study effects of dietary carbohydrates and proteins on the growth of grass carp, we formulated a factorial design of 2×4 diets with medium-size (460 g) and large-size (1970 g) grass carp (Ctenopharyngodon idella). Two die-tary starch levels of 25% and 35% and four protein levels of 22%, 24%, 26% and 28% were fed with medium-size grass carp for 56d with same quantity of food. Two dietary starch levels of 30% and 40% and four protein levels of 18%, 20%, 22% and 24% were fed large-size grass carp. The results showed that the growth performance of the medium-size grass carp increased significantly with increased protein level with the highest effect in the 28% protein group (P<0.05), and the growth performance of 35% wheat starch group was significantly higher than that of the 25% group (P<0.05). The growth performance of large-size grass carp increased significantly with the increased protein level with the peak level at 20% (P>0.05). The growth performance of the 40% wheat starch group was significantly higher than that of the 30% group (P<0.05). No significant negative effects on liver tissues were observed by adding 35% or 40% wheat starch in both groups of grass carp. These results revealed that grass carp can effectively utilize starch to save feed protein when the wheat starch level of the feed was below 35% and 40%, respectively.
2019, 43(5): 992 -1000   doi: 10.7541/2019.118
[Abstract](609) [FullText HTML](135) [PDF 695KB](26)
Abstract:
The effects of dietary Lactobacillus acidophilus on growth performance, digestive enzyme activities, premunition and related enzyme gene mRNA expression of Epinephelus coiodes were assessed in the current study. Seven hundred and twenty healthy fish with an average body weight of (5.60±0.05) g were randomly divided into 8 groups with 3 replicates per group and 30 fish per replicate. The fish were fed a basal diet and an experimental diet that were supplemented with L. acidophilus at the percentage of 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 and 1.2% for 8 weeks, respecti-vely. The WGR and SGR increased first and then decreased with increased L. acidophilus, but they were significantly higher than those of the control group (P<0.05). The FCR reached the lowest value in 0.6% group that was signifi-cantly lower than other group (P<0.05). However, the PER level showed an opposite trend to the FCR. The activities of TRY and AMY in the liver and intestine tended to increase first and decrease thereafter. The liver TRY and AMY mRNA level of the experimental group were significantly higher than those in the control group (P<0.05). Among them, liver amylase and protease activity reached the maximum level at 0.6%, and intestinal protease and amylase activities reached the maximum level at 0.2% and 0.4%, respectively. The fish survival rate significantly increased with the increased Vibrio harvey for 7 days (P<0.05). These results reveal that 0.42% Lactobacillus acidophilus (0.72×108 cfu/mL) in the feed could significantly promote the growth and increase the digestive enzyme activity and disease resis-tance for juvenile grouper.
2019, 43(5): 1001 -1012   doi: 10.7541/2019.119
[Abstract](430) [FullText HTML](113) [PDF 848KB](14)
Abstract:
To investigate the effects of enzymatic hydrolyzed soybean meal (ESBM) on growth performance, liver function and metabolism of largemouth bass (Micropterus salmoides), five isonitrogenous and isoenergetic diets were formulated by replacing fish meal with a plant-based protein source compound (enzymatic hydrolyzed soybean meal: corn gluten meal=10 鲶1) for a 67-days trial. The additions of ESBM in the feed were 0 (E0), 15% (E15), 20% (E20), 25% (E25), 30% (E30) to replace 0, 23.64%, 30.91%, 40%, 47.27% of the fish meal, respectively. In additional, two diets of soybean meal (SBM) and fermented soybean meal (FSBM) were used as the substitute for 20% ESBM, respectively. The results showed that the specific growth rate and weight gain rate of E25 and E30 were significantly higher than those of other groups (P<0.05), and that the feed coefficient ratio of each group had no significant difference (P>0.05). The survival rates of the E25 and E30 groups were lower than other groups. With the increase of ESBM, the viscerosomatic index, hepatic index and the lipid content of body decreased significantly (P<0.05). The specific growth rate of FSBM group was significantly lower than that of E20 group (P<0.05), and viscerosomatic index and hepatic index of FBSM were significantly higher than those of SBM and E20 (P<0.05). The activities of amylase and lipase of intestines increased first and then decreased with the increased ESBM, which were significantly higher than that of the control group (P<0.05). The activity of pepsin in E20 and E30 group was significantly higher than that of the control group (P<0.05). The activity of amylase in FSBM group was significantly higher than SBM and E20 (P<0.05), while the change of intestinal lipase activity was opposite. The activities of liver total-antioxidant capacity (T-AOC), glutamic oxaloacetic transaminase (AST) and alanine aminotransferase (ALT) in all group except liver ALT in E30 group were significantly induced by ESBM (P<0.05), and ESBM significantly reduced liver malondialdehyde (MDA) (P<0.05). The liver MDA content and ALT activities of FSBM group was significantly lower than SBM and E20 group (P<0.05), and the liver AST activity was in the order of E20>FSBM>SBM. The oxygen consumption increased significantly with the increased ESBM, and the nitrogen excretion in E20, E25 and E30 were significantly higher than E0 group (P<0.05). The muscle nitrogen retention rates of E20 and E30 were higher than other groups. ESBM had significant effects on serum free fatty acid (NEFA), total cholesterol (T-CHO), triglyceride (TG), and low density lipoprotein cholesterol (LDL-C) of largemouth bass. Among E20, FSBM and SBM groups, the oxygen consumption in FSBM group was significantly lower than other two groups (P<0.05), while nitrogen excretion was opposite. The serum T-CHO of SBM group was significantly higher than other two groups (P<0.05), while serum LDL-C and muscle lipid were the contrary trend. The serum TG of E20 group was significantly lower than other two groups (P<0.05). These results indicated that the addition of ESBM up to 30% did not harm the growth, and reduced liver oxidative stress to enhance nutrients metabolism. All FSBM, SBM and ESBM have benefits to replace 30.91% fish meal with the best effects by ESBM.
2019, 43(5): 1013 -1020   doi: 10.7541/2019.120
[Abstract](496) [FullText HTML](236) [PDF 534KB](19)
Abstract:
To investigate the effects of ammonia exposure on amino acid metabolism, the Paramisgurnus dabryanus were exposed to 30 mmol/L NH4Cl solution to assess plasma, liver and muscle free amino acid contents. The free amino acid concentrations in plasma, liver and muscle of P. dabryanus were significantly affected by ammonia expo-sure (P<0.05). The plasma free alanine contents significantly increased with increased exposure time (P<0.05). The liver free glutamate contents increased significantly at 12h of ammonia exposure and then obviously decreased at 72h (P<0.05). While the liver free alanine contents remained constant during the first 24h of ammonia exposure, these va-lues remarkably increased at 72h (P<0.05). The muscle free glutamate increased significantly (P<0.05) at 12 hours and then rapidly decreased (P>0.05), and eventually significantly lower than that of the control group at both 72h and 96h (P<0.05). Two peak values of the muscle free alanine contents were found at the 12h and 48h, which were significantly higher than the control values (P<0.05). The remarkably decreased free glutamate values in plasma, liver and muscle of P. dabryanus and the significantly increased glutamine contents and glutamine synthetase activities during ammonia exposure suggest that the glutamate and \begin{document}${\rm{N}}{{\rm{H}}^ +_4}$\end{document} were synthesized into glutamine via glutamine synthetase under high environmental ammonia. With the increased exposure time, the accumulation of free alanine and significantly decreased free glutamate, arginine and proline revealed that P. dabryanus could use certain amino acid metabolism and the formation of alanine to inhibit the production of endogenous ammonia during ammonia exposure.
2019, 43(5): 1021 -1033   doi: 10.7541/2019.121
[Abstract](356) [FullText HTML](134) [PDF 1176KB](19)
Abstract:
This study investigated the morphological development and allometric growth pattern in early life cycle of Konosirus punctatus and illustrated their crucial ecological meanings for survival. Results showed that the average total length of larvae fish was (3.18±0.52) mm with water temperature at (21.5±0.5)℃. The morphological development of K. punctatus was divided into larvae stage (0—43 day age, from hatching to keeled scales appearing) and fry stage (44—55 day age, from keeled scales appearing to scales covering the body). Morphological changes and organ diffe-rentiations mainly occurred in the larval stage. Key morphological characteristics including rostrum length, trunk length, intestinal length, pectoral length and pelvic fin length exhibited allometric growth patterns, in which the growth infle-xion point were 42 day age (TL: 25.47 mm), 24 day age (TL: 15.57 mm), 31 day age (TL: 21.41 mm), 41 day age (TL: 25.47 mm), 42 day age (26.41 mm), respectively. The growth rate in rostrum length and pectoral length changed from the positive allometry (before inflexion point) to the same rate (after inflexion point); the growth rate in pelvic fin length changed from the positive allometry to the negative allometry. These variations could enhance the capacities of breathing, feeding and escaping. The growth rate in intestinal length changed from negative allometry to the same rate, which is related to the dietary conversion of K. punctatus. To adapt to the complex environments, key organs involved in growth and survival were preferentially developed at the early stage, which facilitated the survival rate of K. punctatus. All the findings provide a fundamental evidence for artificial breeding and seedling cultivation in the future.
2019, 43(5): 1034 -1040   doi: 10.7541/2019.122
[Abstract](527) [FullText HTML](180) [PDF 762KB](43)
Abstract:
Gymnocypris potanini Herzenstein, an endemic freshwater species in China, distributes in the upper reaches of the Minjiang River and the Lancang River and some plateau areas with low water temperature even in the summer. The present study investigated the morphological characteristics, formation period of increment, and hatching date of G. potanini. Larvae were identified by COⅠ sequences, which were caught in the Mengtun River at 2015 and 2016. Homology analysis showed that the COⅠ sequence of captured larvae and juvenile were genetically similar to G. potanini and then identified as the G. potanini. The shape of lapilli finally changed into mussel shape, whereas sagittae became wedge-shaped, the long ellipse shape, and eventually changed into long pointed. Then one increment of lapilli by marked temperature was formed every day. The number of marked increments on lapilli were linearly related to the age, and the slopes of the equations were closed to 1.0 (P>0.05). These results demonstrated a daily formation of otoliths increments. By counting the number of daily increment and confirming daily pattern of the increment deposition, the back-calculated hatching dates of the larvae were from 29 June to 15 July in 2015 and from 13 July to 18 August in 2016, indicating that G. potanini has a long spawning period in late summer. These results provided important information on the spawn time of estimation and the basic data for resources conservation of G. potanini.
2019, 43(5): 1041 -1055   doi: 10.7541/2019.123
[Abstract](379) [FullText HTML](180) [PDF 896KB](28)
Abstract:
This study provided technical support for its scientific protection and rational development through exploring the embryonic and larval development characteristics of Ptychobarbus dipogon. The result indicated that the egg diameter reached 3.7—3.9 mm, and egg diameter after water absorbed could reach to 5.1—5.3 mm. The hatching of egg taken 336.02 hours at temperature of 10℃. Based on external morphological characteristics, embryonic development were separated into 7 stages and 34 periods, including cleavage preparing stage, cleavage stage, blastula stage, gastrula stage, neural embryo stage, organ differentiation stage and hatching stage. Characteristics included newly hatching fry with body length of 12.4 mm, 1 day fry after hatching with pectoral fin upwarp, operculum, pigment and underjaw primordial appearance, 3 day fry after hatching with hepatopancreas primordial and alimentary canal appearance, 4 day fry after hatching with gill raker and body pigment cell mass appearance, 5 day fry after hatching with stomatodeum and gill filament appearance, 6 day fry after hatching with pectoral fin fold, dorsal fin fold and pelvic fin fold appearance, 7 day fry after hatching with nose concave and astral form pigment group appearance, 9 day fry after hatching with swim bladder primordial appearance, 11 day fry after hatching with tail fin appearance with pectoral fin trembled, 13 day fry after hatching with swim bladder one room appearance, semicircular canal formed, 17 day fry after hatching with dorsal fin primordial and pectoral fins formed, 21 day fry after hatching with larger hyomandibular of pelvic fin fold, 28 day fry after hatching with spleen appearance, 33 day fry after hatching with pelvic fin appearance, 34 day fry after hatching with scale appearance, and no difference for the fish 85 day after hatching. Egg diameter of Ptychobarbus dipogon is the largest one among Schizothorax fishes, and its perivitelline space is smaller than four major Chinese carps, which may explain by cold environment at the plateau uplift.
2019, 43(5): 1056 -1061   doi: 10.7541/2019.124
[Abstract](364) [FullText HTML](173) [PDF 516KB](22)
Abstract:
To evaluate effects of decontamination time on the nutrient composition, texture and water holding capacity, flavor components and volatile odor substances in bighead carp muscle, the micro-water purification aquaculture system was established in natural lakes for a 2-month trial. The contents of protein and fat in bighead carp muscle were decreased significantly, and the ash showed no significant difference. The content of volatile basic nitrogen and carbonyl in the muscle of bighead carp decreased significantly by prolonging purification time. The hardness of bighead carp muscle texture increased significantly with the extension of purification; the adhesion and chewing of bighead carp muscle were higher than that of the early purification, while the elasticity and recovery in bighead carp muscle were similar to the early experiment. The contents of water-soluble proteins and free amino acids in bighead carp muscle increased at day 20, and then began to decline. We inferred that micro-water purification treatment can significantly enhance the quality of bighead carp and improve the taste and flavor of fish.
2019, 43(5): 1062 -1071   doi: 10.7541/2019.125
[Abstract](439) [FullText HTML](194) [PDF 743KB](14)
Abstract:
Family selection has emerged as a crucial tool for selective breeding in aquaculture. The current artificial selection for Japanese scallop (Mizuhopecten yessoensis) predominantly focused on the apparent characters, e.g. growth, shell color and survival rate. Little studies of selective breeding were based on nutritional value of adductor muscle. The present study investigated the growth performance, the fatty acid composition, the content of carbon and nitrogen and C/N ratio of adductor muscle in distinct selective breeding families of M. yessoensis and explored the correla-tion between C/N ratio and fatty acid content. The results demonstrated that the growth features of the families 25#, 54# and 19# were superior to those of 32#, 87# and 93# (P<0.05). No significant difference of the total major fatty acids was observed between distinct families, but the relative abundance of the major fatty acids was obviously diffe-rent between distinct families as PUFA>SFA>MUFA. The amounts of EPA and DHA based on dry weight of adductor muscle in M. yessoensis varied from 3.59 to 4.09 mg/g, and from 3.03 to 3.46 mg/g, respectively. The relative abun-dance of both EPA and DHA ranged between 47.19% and 49.32% of the total fatty acids. Moreover, the content of carbon and nitrogen of adductor muscle in distinct families of M. yessoensis remained constantly with (39.21±0.04)% and (10.62±0.16)%, respectively. The C/N ratio was (3.70±0.06). The further correlation analysis showed that the C/N ratio was positively related to the growth of adductor muscle in distinct families. On the contrary, a prominently negative correlation existed between the C/N ratio and the content of TFA, SFA, PUFA, EPA or DHA with the most evident one between C/N ration with DHA. Our results indicated that the fatty acid composition, the content of C and N and the C/N ratio of adductor muscle could be used for selective breeding of M. yessoensis. These findings provide important implications for the broad development of the selective breeding in scallops.
2019, 43(5): 1072 -1080   doi: 10.7541/2019.126
[Abstract](564) [FullText HTML](141) [PDF 956KB](112)
Abstract:
To reveal the characteristics of external morphology and internal organ during the growth and development of larvae to juveniles of pearl oyster Pinctada fucata and the relationship between morphology, organs and motion, ingestion behavior, optical microscopy was used for observations and nonlinear regression parameters were used for descriptions. The results showed that during the normally larval rearing, the growth of shell length was accelerated positi-vely, the growth of shell height was decelerated positively, the growth of hinge length was accelerated negatively, the growth of shell height was faster than that of the shell length, and the growth of hinge length was slower than that of the shell length. When the larvae grown to a shell length of (209.26±9.22) μm, the internal organs began to change, the velum gradually degene-rated and developed into a gill, and the foot gradually formed. when the shell length reached (234.30±14.00) μm, the secondary shell appeared and the external morphology gradually changed to the juvenile. In the juvenile stage, the growth of gill filament length, gill filament distance and number of gill filament were slower than that of shell length. The larvae swim and filter microalgae by beating their cilia. When swimming, the double shells on the top of the larvae opened the umbo toward the bottom, and the velum projecting from back of the shell is used to propel the body. Larvae swim around clockwise with a certain radius in the vertical direction with a spiral either rising or falling. In the juvenile stage, the reciprocating expansion of the foot and the filtration of the sputum conducted the crawling and the feeding, respectively. During the metamorphosis of larvae stage, the velum is degraded, the motor function of the metamorphosis larvae is reduced, the feeding function has disappeared, larvae relied on reserved energy to complete growth and organ development, which is an important step in larval rearing.
2019, 43(5): 1081 -1091   doi: 10.7541/2019.127
[Abstract](460) [FullText HTML](183) [PDF 1180KB](19)
Abstract:
To investigate pathological features of ichthyophthiriasis in Schizothoracine fishes, we performed a pathological comparison between Gymnocypris przewalskii przewalskii and Schizopygopsis pylzovi infected with Ichthyophthirius multifiliis. The infection of I. multifiliis resulted in high morbidity and mortality rate in G. p. przewalskii and S. pylzovi. The mortality rate of G. p. przewalskii and S. pylzovi increased dramatically at 3 dpi (day post infection) and then decreased gradually. All the infected G. p. przewalskii died after 8 dpi. The mortality rate of S. pylzovi was 97.3% with only two S. pylzovi survived after 14 dpi. There were lots of small white spots on the skin of both infected fish species but with significantly different Symptoms. A large amount of mucus were secreted in G. p. przewalskii to form gelatinous layer on the skin. Tomonts in different developmental stages were embedded in the gelatinous layer. In the infected S. pylzovi, necrosis and exfoliation occurred in the epithelium of the caudal fin and dorsal fin, and ulceration appeared due to the secondary infection by bacteria on the skin. The anatomic examination showed similar pathologi-cal changes in liver of G. p. przewalskii and S. pylzovi with the liver color from light red to faint yellow. Meanwhile, gallbladder was swollen and enlarged in both species. Histological sections and electron microscopy demonstrated the adhesion of gill filaments in infected G. p. przewalskii and S. pylzovi, and the gill lamellas and gill epithelia cells were exfoliated. In G. p. przewalskii, I. multifiliis parasite created huge cavities in the epidermis and altered the structure of the skin epidermis. Skin epidermal cells of infected S. pylzovi showed evident vacuolation, the original tight structure was completely lost, and boundaries between epidermis and tunicae propria was blurred. These results indicated simi-lar targeted organs by I. multifiliis infection but with different symptoms in G. p. przewalskii and S. pylzovi that may explain by the long-term adaptation to salt water and freshwater environments by G. p. przewalskii and S. pylzovi, which laid the foundation to study host-pathogen interaction in Tibetan highland fishes.
2019, 43(5): 1092 -1097   doi: 10.7541/2019.128
[Abstract](453) [FullText HTML](110) [PDF 712KB](13)
Abstract:
This study re-described Myxobolus wulii (Wu & Li) Landsberg & Lom, 1991 and compared its strains in different sections of Yangtze River Basin (Chongqing strain, Hubei strain and Jiangsu strain) based on morphological and molecular (18S rDNA) data. The results showed that the spores and polar capsules of Chongqing strain were slightly smaller than those of Hubei strain, and that polar capsules and spores of Chongqing strain were equal in size while they were unequal for Hubei strain. The similarities and genetic distances among the three strains of M. wulii were 99.2%—99.9% and 0.002—0.007, respectively. Phylogenetic analysis showed that the sequences of M. wulii formed a poor geographical structure as well as poor host-original structure, but a strong parasitic site structure. The sequences of M. wulii clustered into two lineages: gill-parasites clade and hepatopancreas-parasites clade, indicating that the individuals of M. wulii have closer relationship with the same site of host. Moreover, the gill-parasites clade diverged earlier than hepatopancreas-parasites clade, which might be related to the evolution of external-parasites to internal-parasites. These data inferred that the gill-parasites population might be the earliest migrates of M. wulii.
2019, 43(5): 1098 -1103   doi: 10.7541/2019.129
[Abstract](396) [FullText HTML](190) [PDF 914KB](13)
Abstract:
Microcystis strains isolated from bloom-forming ponds were analyzed based on gvpA-C intergenic sequence and 16S rDNA. Several gvpA-C intergenic sequences shared an 172—176 bp extra sequence. An alignment of different types of 0.27 kb sequences, exclusive of the extra sequence, showed over 50 substitutions, whereas in a 0.69 kb hot spot region of 16S rDNA only 8 substitutions were identified. Compared to 16S rDNA, the gvpA-C intergenic sequence was generated by one-step PCR without contamination from co-existing bacteria and showed much higher variability, therefore should be useful in typing of Microcystis. Due to horizontal gene transfer, the two sets of types demonstrated an intersecting relationship. In addition, Microcystis gvpA-C intergenic sequences with or without the extra sequence formed two distinct clusters in a phylogenetic tree.
2019, 43(5): 1104 -1113   doi: 10.7541/2019.130
[Abstract](529) [FullText HTML](226) [PDF 986KB](44)
Abstract:
Aquaponics, a new type of sustainable, cyclic and zero-emission composite farming system, has become an effective method to solve the agricultural ecological crisis because of its good ecological environment effect and food safety guarantee. The 16S rRNA gene (V3-V5 region) of microorganisms in aquaculture environment and roots was sequenced by using Illumina high-throughput sequencing platform under the typical aquaculture pond mode in Northwest China. The comparison of microbial community structure and diversity showed that the total effective sequence of bacteria was 56444, and the average number of annotated OTU was 945. The dominant bacteria were phyla Proteobacteria, Bacteroidete, Firmicutes and Cyanobacteria. The dominant bacteria in MD.R and JH.R were phyla Bacteroidetes and Proteobacteria, respectively. There were 165 OTUs in the six samples with the highest OTU in JH.KX (137), the lowest one in JH.R (30), and the same OTU (85) in MD.R and JH.C. Rhizobia, fish pathogenic bacteria, cold-resistant bacteria and bacteria that decompose organism and reduce heavy metals and toxins were detected by annotating the OTUs. This study revealed the microbial community structure and its ecological regulation mechanism under the aquaponics model.
2019, 43(5): 1114 -1121   doi: 10.7541/2019.131
[Abstract](1087) [FullText HTML](111) [PDF 854KB](19)
Abstract:
In order to prove up the spatial distribution patterns of Sgassum vachellianum in Northern Zhejiang nearshore typical reefs, investigations were conducted on three reef belts with 12 reefs from the end of May to the beginning of June, 2016. Researchers carried out vessel-mounted observations and collected samples with SCUBA (Self-Contained Underwater Breathing Apparatus) to find out and compare the differentia of horizontal and vertical distribution features of S. vachellianum in adult stages. The results showed that (1) at the area scale, water environment with high turbidity and high wave energy inhibited the growth and spread of S. vachellianum which could merely be found on the second narrow reef belt. According to the growth characteristics of minimum appropriate water temperature with 10℃, it can be inferred that the northernmost island of Zhoushan Archipelago is the northernmost spread limit of endemic S. vachellianum to China. (2) At the site scale, the factor of wave exposure might explain the reason why S. vachellianum were sparse in southeast and were rich in northwest of reefs. The average height of S. vachellianum was only 26.3 cm on the four reefs of the second reef belt, which indicates high wave energy is not suitable for its growth. (3) Within the site scale, the North Yushan Island on the second reef belt was with lowest turbidity so that S. vachellianum were widespread, which could even be found in depth of 6.4 m. However, coastal waters with high turbidity withheld vertical distribution of S. vachellianum. As the result showed the average height of S. vachellianum decreases with depth, which can be inferred that S. vachellianum were intolerance of intense light, but light is a major factor for its distribution. Compared with the vertical distribution of Sargassum horneri in this region, S. vachellianum were adaptive to the environment with high turbidity and high sediment. Therefore, the change of inhibited water environment has driven S. vachellianum to the edge of extinction. By studying the causes of the spatial distribution of S. vachellianum, the decline of algae fields and the trend of variation, the conclusion can be drawn that S. vachellianum are suitable for artificial transplantation in Northern Zhejiang coastal area. The findings can provide meaningful references for the protection and restoration of algae fields.
2019, 43(5): 1122 -1131   doi: 10.7541/2019.132
[Abstract](508) [FullText HTML](217) [PDF 860KB](30)
Abstract:
This study analyzed the external morphology, vegetative and reproductive structure, growth process, biomass variation, mature individual proportion, R/T index, as well as the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (rbcL) gene and the partial cytochrome coxidase Ⅰ (COⅠ) gene sequences of Gloiosiphonia capillaris (Hudson) Carmichael populations collected in the coast of Heishijiao, Fujiazhuang, Shicao, Jinshitan, Zhangzidao and Haiyangdao in Dalian. The results indicated that the gametophytes of G. capillaris were androgynous, solitary or caespitose habit, and that the main axes were erect, disciformi affixus, gelatinous in texture, red or purplish red. The length and width of thallus collected in Zhangzidao and Haiyangdao were significantly higher than those in other sites. Thallus was composed of cortex that had 6—10 cell layers and medulla that was consisted of many rhizoidal filaments. The size of mature cystocarp was small and protruded from the thallus. Cystocarps were spherical or hemispherical, and often became a group with 2—4 members. The maximum biomass of gametophyte appeared in June with an average value of 3.628 g/m2. The proportions of mature individuals increased gradually from March to June and got 100% in June. The gametophyte growth cycle was from March to July, and the temperature property was temperate. According to the phylogenetic tree of rbcL gene sequences, there was no sequence divergence among the 6 sites and clustered in a single monophyletic subclade with the sample from Canada. There was also no sequence divergence among the 6 sites based on the phylogenetic tree of COⅠ gene sequences. The samples were clustered in a single monophyletic subclade and identified as G. capillaris.
2019, 43(5): 1132 -1138   doi: 10.7541/2019.133
[Abstract](417) [FullText HTML](126) [PDF 1413KB](19)
Abstract:
To explore the species diversity of the marine diatom genus Thalassiosira Cleve, several monoclonal strains were established from Daya Bay, north coast of the South China Sea. The morphology of the cells was examined by light and scanning electron microscopy. The hypervariable D1-D3 region of the nuclear large-subunit ribosomal DNA and the relatively conserved region of the nuclear small-subunit ribosomal DNA were sequenced and used for phylogenetic relationship analysis. Combined the morphology and molecular data, a new species, T. flabellata sp. nov. X H Guo, Y Q Guo & Y Li was described. The cells normally form short chains or solitary. A central fultoportula, one ring of marginal fultoportulae and one marginal rimoportula are present on the valve face. This species is characterized by fasciculate areolae on the valve.
2019, 43(5): 1139 -1146   doi: 10.7541/2019.134
[Abstract](455) [FullText HTML](144) [PDF 1965KB](21)
Abstract:
This study explored the nitrogen-fixing microbial community structure, diversity and nitrogen fixation activity in urban landscape water body, and the nitrogen-fixing contribution of nitrogen-fixing cyanobacteria in water from Muye Lake and People’s Park in Xinxiang city. Physical and chemical indicators are eutrophic in these two lakes. This study measured 16S rDNA and Nitrogenase nifH gene of microorganism by high-throughput sequencing, and determined nitrogen fixation rate of nitrogen fixing microorganisms in two lakes by the acetylene reduction assay. A total of 32 phyla and 275 genera were detected in the prokaryote groups, and a total of 9 phyla and 66 genera were detected in the nitrogen-fixing microorganisms in Muye Lake. A total of 31 phyla and 238 genera were detected in the prokaryote groups; a total of 4 phyla and 13 genera were detected in the nitrogen-fixing microorganisms in the water column of the People’s Park. Nitrogen-fixing cyanobacteria accounted for 3% in the Muye Lake and 9.3% in People’s Park. The richness of Nitrogen-fixing microorganisms in Muye Lake was significantly higher than that of People’s Park. The nitrogen fixation activity in the two lakes was similar. It is speculated that nitrogen fixation activity may be inhibited in eutrophic water.

### 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

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