Institute of Hydrobiology, Chinese Academy Of Sciences
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The Morphology and Phylogeny of ThreeDiophrysCiliates Collected from the Subtropical Waters of China, Including a New Species (Ciliophora; Euplotia)
No full textThreeDiophrysspecies,D. quadrinucleatan. sp.,D. oligothrixBorror, 1965 andD. scutum(Dujardin, 1841) Kahl, 1932, were identified from the subtropical brackish waters in China, their morphology was investigated using live observation and protargol impregnation.D. quadrinucleatan. sp. can be distinguished from the congeners by four ellipsoidal macronuclear nodules. Phylogenetic analyses show that the three species with single marginal cirrus are closely related, namelyD. quadrinucleatan. sp.,D. apoligothrixSonget al., 2009 andD. japonicaHu, 2008. Our population ofD. oligothrixcorresponds very well with previous populations in both living morphology and ciliature. However, the SSU rDNA sequences of three well-described populations differ from each other by 11 to 18 nucleotides, indicating that there might be cryptic species inD. oligothrix. Moreover, we provided a detailed description of the symbiotic bacteria/archaeobacteria (?) concentrated on the back surface ofD. scutumbased on the present population, which was either overlooked or misinterpreted as cortical granules previously
Spatial and interspecific comparisons of the reproductive biology of two species of co-occurring freshwater shrimps (Decapoda: Caridea: Palaemonidae) in the Three Gorges Reservoir, China
No full textExopalaemon modestus (Heller, 1862) and Macrobrachium nipponensis (De Haan, 1840) (Palaemonidae) are ecologically and commercially important fishery resources in the Three Gorges Reservoir (TGR), China, and co-occur in demersal habitats. Little information is available on their biology. We compared the reproductive traits of both species on the upper, middle, and lower sections of the TGR. Both species differed in mean size at maturity, which increased from upper to middle and lower sections. Sex ratios were significantly biased toward females, but no significant differences were observed among the three sites for either species. Both species displayed an obvious trade-off between embryo size and fecundity, with the size of embryos being the smallest but with the highest fecundity at the upper section, followed by the middle and lower sections. Exopalaemon modestus spawned from early April to late September, with a peak in May and June, whereas M. nipponensis spawned from late April to early October with a peak in June and July. The spatially distinct reproductive traits, which were concordant across species, are likely related to differences in habitat characteristics such as water flow. We suggest that management strategies should account for the reproductive biology of the two species in order to maintain a sustainable fishery in the reservoir
A new contribution to the taxonomy and molecular phylogeny of three, well-known freshwater species of the ciliate genus Spirostomum (Protozoa: Ciliophora: Heterotrichea)
No full textMembers of the heterotrich genus Spirostomum are commonly found in freshwater or low salinity biotopes. In the present study, three species (S. minus, S. subtilis and S. teres) collected from freshwater habitats in Qingdao, China, are investigated using morphological and molecular methods. Detailed morphometric data are documented and improved diagnosis are supplied based on a combination of previous and present studies. In addition, small subunit ribosomal DNA (SSU rDNA) sequences are obtained from the clonal cultures. Phylogenetic analyses show that all three species are placed in the Spirostomum clade. However, isolates of the morphospecies S. minus are divided into two paraphyletic clades, while 'populations' of the nominal species, S. teres, are placed in at least four separate groups in the tree. After comparing morphological and molecular differences in closely related forms available, we hypothesized that S. minus and S. teres might represent species complexes. A key to the identification of the ten valid species of Spirostomum is also supplied
Assessing the intestinal bacterial community of farmed Nile tilapia (Oreochromis niloticus) by high-throughput absolute abundance quantification
No full textIntestinal microbiota studies based on high-throughput sequencing have attracted increasing attention due to its vital impact on host health. However, the taxonomical profile in relative proportion does not reflect the quantity of the intestinal bacteria and the inter-sample differences among taxa. In this study, we applied a high-throughput absolute abundance quantification method that used an internal standard strain to simultaneously obtain both the relative and absolute abundances in the intestinal bacterial community of farmed Nile tilapia (Oreochromis niloticus). The results showed that the structure, relative and absolute abundances, and function of the intestinal indigenous microbiota didn't change significantly after adding a low concentration of internal standard strain, and a comprehensive quantitative intestinal bacterial ecology was obtained. We first found that the total absolute abundance of the intestinal indigenous bacteria in farmed Nile tilapia was 2.95 x 10(8) cells g(-1), and most genera concentrations were in the range of 10(3) to 10(5) cells g(-1). The intestinal bacterial community was dominated by Cetobacterium with a concentration of 10(8) cells g(-1), followed by Plesiomonas, Romboutsia, and Escherichia-Shigella with concentrations of over 10(7) cells g(-1). The potential intestinal pathogens Aeromonas and Streptococcus reached 10(5) cells g(-1) in the tilapia intestines, while the potential probiotics such as Lactobacillus and Enterococcus with a high concentration of over 10(6) cells g(-1) were detected. Furthermore, PICRUSt analysis revealed that functional genes involved in membrane transport, carbohydrate metabolism, and amino acid metabolism were enriched in the intestinal microbiota of tilapia. This study characterized the intestinal quantitative bacterial ecology of farmed Nile tilapia, providing foundational support for an in-depth understanding of the intestinal microbiota and its interaction mechanism with the host
Metacommunity Structures of Macroinvertebrates and Diatoms in High Mountain Streams, Yunnan, China
No full textThe metacommunity concept has received increasing interest in the past two decades. However, there has been limited research examining metacommunity structure of communities in high mountain streams. These ecosystems are often physically constrained and can display large environmental gradients within a relatively small spatial extent. Here, we examined metacommunity structures of stream organisms in a high mountain region, which is part of the Hengduan Mountains region in Southwest China. Macroinvertebrates and diatoms were collected from six streams in two opposite aspects of the same mountain with different connectivity between streams. On the west aspect, streams are tributaries of a river (i.e., river-connected) while streams flow into a lake (i.e., lake-connected) on the east aspect. We used Elements of Metacommunity Structure analysis to explore the metacommunity structuring of these two biological models. We also compared the contribution of dispersal and environmental filtering in structuring metacommunities by looking at Euclidean, network, topographic, and environmental distances. Communities of diatoms and macroinvertebrates were structured with clear turnover on both aspects. Further, diatom communities exhibited Clementsian structure on both aspects. Macroinvertebrates exhibited different metacommunity structures on the river-connected aspect (Quasi-Clementsian) and lake-connected aspect (Clementsian). Our results indicated that on the lake-connected aspect, environmental filtering had a stronger association with community dissimilarity than on the river-connected aspect for both macroinvertebrate and diatom communities. Diatom communities were more influenced by environmental filtering on the east aspect with weakened network connectivity compared with those on the west aspect. Our results also emphasized the potential effects of biotic interactions between macroinvertebrates and diatoms on shaping community structures of one other. Our study provides substantial elements to further understand metacommunity structure and highlights the necessity of future research to reveal the underlying mechanisms of community structuring in these remote ecosystems
Converting alfalfa pasture into annual cropland achieved high productivity and kept soil organic carbon in a semiarid area
No full textConverting alfalfa (Medicago sativa L.) into annual cropland (rotated cropland, RC) is commonly done to reuse degraded alfalfa pasture. However, it is a big challenge for RC to achieve high productivity and maintain high soil organic carbon (SOC) to the levels achieved by previous alfalfa pasture. We converted a long-term alfalfa pasture into RC in 2010, and studied the effects of fertilization on soil moisture, crop productivity, and SOC in the RC and in continuous cropland (CC), both under plastic film mulching, from 2010 to 2018. Before the conversion, alfalfa pasture had a higher SOC (12.3%) and total N (7.7%) than CC. However, not only severe soil desiccation occurred, but the available P and inorganic-N were only about 39.4 and 25.1% of levels for CC. After the conversion, soil moisture in RC (measured at 0-0.6 m depth) was up to CC levels only after 1 year, and was restored to 95.3 and 69.2% of CC levels at 0.6-2 and 2-5 m depths only after 9 years. Crop yield and biomass in RCF (RC with fertilization) were comparable to those for CCF (CC with fertilization) after two years from conversion due to the increased available P and inorganic-N, and sufficient soil moisture restoration at 0-0.6 m depath. SOC in RC decreased by 8.1% over the 9 years, while RCF consistently kept SOC levels up to those of pre-conversion alfalfa pasture. These findings help to eliminate concerns about the continuously low production and rapid decline of SOC in croplands converted from alfalfa and suggest ways to support sustainable high-productivity and high SOC sequestration in dryland farming
Host-microbiota interactions and responses to grass carp reovirus infection in Ctenopharyngodon idellus
No full textGut microbiota could facilitate host to defense diseases, but fish-microbiota interactions during viral infection and the underlying mechanism are poorly understood. We examined interactions and responses of gut microbiota to grass carp reovirus (GCRV) infection in Ctenopharyngodon idellus, which is the most important aquaculture fish worldwide. We found that GCRV infection group with serious haemorrhagic symptoms (G7s) showed considerably different gut microbiota, especially with an abnormally high abundance of gram-negative anaerobic Cetobacterium somerae. It also showed the lowest (p < 0.05) alpha-diversity but with much higher ecological process of homogenizing dispersal (28.8%), confirming a dysbiosis of the gut microbiota after viral infection. Interestingly, signaling pathways of NOD-like receptors (NLRs), toll-like receptors (TLRs), and lipopolysaccharide (LPS) stimulation genes were significantly (q-value < 0.01) enriched in G7s, which also significantly (p < 0.01) correlated with the core gut microbial genera of Cetobacterium and Acinetobacter. The results suggested that an expansion of C. somerae initiated by GCRV could aggravate host inflammatory reactions through the LPS-related NLRs and TLRs pathways. This study advances our understanding of the interplay between fish immunity and gut microbiota challenged by viruses; it also sheds new insights for ecological defense of fish diseases with the help of gut microbiota
Screening of the dominant Chlorella pyrenoidosa for biofilm attached culture and feed production while treating swine wastewater
No full textThis research 12 microalgal species were screened for biofilm attached culture in the treatment of anaerobically digested swine wastewater (ADSW). The influence of ADSW on biomass productivity and removal efficiencies were evaluated using biofilm attached culture with the selected Chlorella pyrenoidosa. The variation of nutritional components from algal cells were further analysed to evaluate the potential applications of C. pyrenoidosa. The results showed that C. pyrenoidosa had the highest tolerance to ADSW, and the highest removal efficiencies for wastewater pollutants were reached when cultured in 5 times diluted ADSW. These test conditions resulted in an algal cell biomass composed of 57.30% proteins, 14.87% extracellular polysaccharide, 3.08% crude fibre, 5.57% crude ash, 2.85% moisture. Amino acids in proteins contained 21.73% essential amino acids and the EAA/NEAA value was 0.64. The essential amino acid score indicates that the selected C. pyrenoidosa could be a good protein source for feed addition
Dibutyl phthalate adsorption characteristics using three common substrates in aqueous solutions
No full textIn recent years,the presence and adverse impacts of phthalic acid esters m aquatic environments have gained increasing attention.This work investigated the adsorption behavior of a typical phthalic acid ester,dibutyl phthalate(DBP),onto steel slag,gravel,and shell sand(substrates commonly used in constructed wetlands).The influence of dissolved organic matter(DOM)on DBP adsorption was investigated using humic acid as a proxy for DOM.The results demonstrated that the adsorption of DBP to three substrates reached equilibrium within 96 h,and the adsorption kinetics were well fitted by a pseudo-second-order model.The DBP adsorption isotherms were best fitted by the Langmuir adsorption model.The DBP adsorption capacity decreased in the order of steel slag>gravel>sheII sand,with values of 656 mg/kg,598 mg/kg,and 6.62 mg/kg at 25°C,respectively.DBP adsorbed to the surface of all substrates in a monolayer via an endothermic process.The DBP adsorption capacities of steel slag and gravel decreased as the DOM content increased.The DBP adsorption mechanisms to steel slag and gravel mainly involved the surface coordination of DBP with-OH or-COOH groups and electrostatic interactions.The results of this work suggest that steel slag and gravel may be ideal substrates for use in constructed wetlands to treat wastewater polluted with DBP
三维荧光分析评价腐殖酸高级氧化前处理效果的研究
No full text地表水中腐殖酸类物质在常规水处理过程中很难被降解去除,大部分残留组分会在后期加氯消毒过程中产生消毒副产物等对人体有害的物质。选取紫外(UV)辐照、过硫酸根(peroxydisulfate,PDS)和双氧水(H2O2)高级氧化过程,对腐殖酸进行部分氧化降解,考察了不同的高级氧化作用对腐殖酸的处理效果。三维荧光光谱(fluorescence excitation emission matrix,FEEM)分析结果表明, UV/PDS共同作用可在10 min内极大程度地去除腐殖质类难降解组分,可减轻腐殖质带来的嗅味与色度问题,并可减少后续消毒处理过程中产生消毒副产物的问题