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1.
The composition and distribution of benthic, periphytic and planktonic rotifers in different habitatsin Krottensee were investigated. Sixty-five rotifer taxa were identified, their relative abundance estimated. Classification of the data set by cluster analysis allowed the recognition of distinct habitat groupe con-fined to acid bog ponds, macrophytes, sediments, and open water. Five groups of rotifer taxa were identifiedon the basis of their habitat preferences and the occurrence of the taxa. Highest diversities were found onmacrophytes and in acid bog ponds.  相似文献   

2.
We evaluated the seasonal variation in plankton community composition in an artificial lake. We conducted microscopic analysis and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNAand 18S rRNAgenes to characterize the plankton community. The clustering of unweighted pair group method with arithmetic mean (UPGMA) was then used to investigate the similarity of these plankton communities. DGGE fingerprinting revealed that samples collected at the different sites within a season shared high similarity and were generally grouped together. In contrast, we did not observe any seasonal variation based on microscopic analysis. Redundancy analysis (RDA) of the plankton operational taxonomic units (OTUs) in relation to environmental factors revealed that transparency was negatively correlated with the first axis (R=-0.931), and temperature and total phosphorus (TP) were positively correlated with the first axis (R=0.736 and R=0.660, respectively). In conclusion, plankton communities in the artificial lake exhibited significant seasonal variation. Transparency, phosphorus and temperature appear to be the major factors driving the differences in plankton composition.  相似文献   

3.
The intestinal bacteria of vertebrates form a close relationship with their host.External and internal conditions of the host,including its habitat,affect the intestinal bacterial community.Similarly,the intestinal bacterial community can,in turn,influence the host,particularly with respect to disease resistance.We compared the intestinal bacterial communities of grass carp that were collected from farm-ponds or a lake.We conducted denaturing gradient gel electrophoresis of amplified 16S rRNA genes,from which 66 different operational taxonomic units were identified.Using both the unweighted pair-group method with arithmetic means clustering and principal component analysis ordination,we found that the intestinal bacterial communities from the two groups of pond fish were clustered together and inset into the clusters of wild fish,except for DF-7,and there was no significant correlation between genetic diversity of grass carp and their intestinal bacterial communities(Mantel one-tailed test,R=0.157,P=0.175).Cetobacterium appeared more frequently in the intestine of grass carp collected from pond.A more thorough understanding of the role played by intestinal microbiota on fish health would be of considerable benefit to the aquaculture industry.  相似文献   

4.
Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species,Hardyoides damaensis,Meringaspis damaensis and Rhyssometopus (Rodtrifinis) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi,the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope ) into a deep-water of oxygen-poor setting (basin).  相似文献   

5.
Middle and Late Cambrian trilobite faunas from the Dama section in western Hunanare are composed of 63 genera and subgenera, 84 species, and two forms of gen. et sp. indetermined. Which include a mixture of cosmopolitan agnostoids and polymeroids. Three new species, Hardyoides damaensis ,Meringaspis damaensis and Rhyssomelopus (Rodtrifinis ) nitidus, are described by present author in 2004. Besides, Erixanium is recognised for the first time in study area, which is significant for biostratigraphical correlation of the Late Cambrian in the Austalo-Asia region. According to distribution regularity vertical, the Middle and Late Cambrian trilobites can be divided into 9 trilobite communities for the Dama section. Based on the trilobite communities analysis, the author concludes that from the east Mt. Lailong to Dama through Fenghuang, further east, reach in Chenxi.the palaeoenvironments were changed from a shallow-water of oxygen-rich (platform margin slope) into a deep-water of oxygen-poor setting (basin).  相似文献   

6.
Mountain lakes represent essential stages for aquatic species on their way colonizing habitats of more elevated regions. Despite extensive biological and chemical study, only little has been reported about the species number and density of freshwater molluscs in these waters. The article presented here elucidates the dispersal of aquatic gastropods and bivalves in 12 mountain lakes that are commonly situated in the Eastern Alps, Austria. Molluscs were recorded at 120 sample points, where a total of 13 species (8 gastropods and 5 bivalves) could be determined. Species distribution data as well as results from contemporarily conducted physico-chemical factor recording were subject to weighted average analysis. In addition, a global marginality coefficient indicating the particularity of a habitat inhabited by a focal species as well as a global tolerance coefficient expressing the width of a niche occupied by this species were computed. Species-environment relationships exhibited that species number and specific density decrease with increasing geographic altitude, declining water temperature, and decreasing amount of submerged vegetation. Whilst waters of the montane altitude level are partly charcterized by high number of mollusc species (> 10), lakes of the subalpine altitude level commonly bear 1 or 2 species with <<1 ind./m2. As proposed by the results of statistics, 9 of the 13 mollusc species are characterized by a pronounced behaviour as specialists with respect to most environmental factors. The four remaining species, Pisidium casertanum, Galba truncatula, Radix labiata, and Radix balthica, act as generalists which increases their pioneering role in the long-term occupation of the Central-alpine region.  相似文献   

7.
根据2010~2011年中街山列岛水域4个季节的渔业资源调查资料,分析了该水域虾类资源密度和群落多样性,并探讨了底层温度、底层盐度和水深对虾类数量分布和多样性的影响.结果表明:共有虾类20种,隶属于9科18属;广温广盐种无论在种类数还是尾数密度与生物量均占主导地位;虾类生物量和尾数密度在季节分布上,以冬季最高,冬季均与春、夏和秋三季呈显著差异(p值<0.05);平面分布上,生物量与密度指数总体上呈南北高、中间低,东部高西部低的特征;生物量与平均底温显著相关(P<0.05),与平均底盐和水深相关性较差(p值>0.05);葛氏长臂虾、细巧仿对虾、中国毛虾、日本鼓虾和中华管鞭虾为四季的优势种,且均属广温广盐种;虾类群落Margalef丰富度指数为0.61~1.09,Shannon-Wiener多样性指数为0.76~1.31,Pielou均匀度指数为0.50~0.70,其中丰富度指数和多样性指数春季与冬季均存在显著差异(P<0.05),均匀度指数秋季与冬季存在显著差异(p值<0.05).  相似文献   

8.
There are 463 species of woody plant, belonging to 166 genera and 70 families in Shanxi, North China. The floristic composition types of genera and species are abundant, in which the compositions distributed in temperate zones (including North Temperate, Old World Temperate and Temperate Asia), having 62 genera, are dominant and account for 38.27% in total genera (except for Cosmopolitan), and they are major constructive or dominant species of vegetation in Shanxi. The floristic compositions of woody plants of Shanxi, Hebei, Beijing, Shandong, Henan, Jiangxi and Inner Mongolia were studied comparatively by using diversity index, principal component analysis (PCA) and group-average clustering, respectively. The floristic composition of Shanxi was considerably similar to that of Hebei, Beijing and Shandong because they shared a lot of genera, specially genera distributed in temperate regions, such as Rosa, Quercus, Populus, Salix, Acer, Ulmus, Pinus etc. and their eco-environment were considerably similar. However, the flora of Shanxi was comparatively different from that of Henan, Jiangxi and Inner Mongolia by reason that there were distinct differences among their eco-geographic conditions, floristic compositions and constructive or dominant species of dominant vegetation types. Supported by Shanxi Returned Oversea Scholar Foundation, China  相似文献   

9.
The 16S and 18S ribosomal ribonucleic acid genes of microbial organisms collected from the contrasting environments (temperature, salinity, silicate, phosphate and nitrate, p <0.05) of the inner and outer basins of Kongsfjorden (Spitsbergen, Arctic) were studied using polymerase chain reaction-denaturing gradient gel electrophoresis(DGGE) fingerprinting. Comparison of the microbial fingerprints and the physicochemical parameters revealed that molecular methodology exhibited a greater sensitivity. Sequences obtained from bacterial DGGE were affiliated with four main phylogenetic groups of bacteria:Proteobacteria(Alpha, Beta and Gamma), Bacteroidetes, Verrucomicrobia and Cyanobacteria. The relationships between the genotype distribution of these microbes and associated biotic/abiotic factors, revealed by canonical correspondence analysis, showed that Station 1 at 30 m (outer fjord) was grouped separately from the other sites. This difference could be a consequence of the thermocline and base of the euphotic layer at this depth where the Atlantic and Arctic-type waters overlapped.  相似文献   

10.
The development of modern agriculture has resulted in much homogenization of the landscape consisting of large patches of farmland,so small remnant non-crop habitats especially linear corridors play an important role in the conservation of species and the maintenance of ecosystem functions.However,little attention has been paid to the effects of corridors structural characteristics on the plant species restricted to such habitats.In this study,we selected three types of corridors including ditch,hedgerow and road,and ana-lyzed their structural characteristics.The plant species presented in these corridors were investigated,and the species diversity,abun-dance and frequency were estimated.Moreover,spatial arrangements of corridors were classified into different types to discuss whether there were significant effects of corridor network on plant distribution.The results show that three types of corridors have different ef-fects on plant species composition and diversity.The one-one combined corridor networks and total network associated by three corri-dors have more complex structural features than each single type of corridor.However,there is no strong correlation between the corri-dor networks with their plant species.We suggest that carrying out a pointed vegetation survey at corridor intersections to further test the relationships between structural features of corridor and plants is necessary.  相似文献   

11.
12.
Luidia Forbes (Paxillosida: Luidiidae) are common soft bottom sea stars with 49 described species. Because of substantial morphological diversity, the taxonomy of the genus is complex and hasn’t been resolved definitely. In order to resolve general taxonomic issues, and determine species boundaries and phylogenetic relationships within the genus Luidia, the sequences of cytochrome oxidase subunit I (COI) gene from 24 specimens of Luidia, belonging to eight taxa in Chinese waters, were studied. Three sequences of two species in genus Luidia from GenBank were used to analyze the phylogenetic relationships. The molecular phylogeny exhibited three main clades, each with strong bootstrap support: Clade A including Luidia quinaria from the Sea of Japan; Clade B including seven nominal species (L. quinaria von Martens, L. yesoensis Goto, L. changi Liu, Liao and Li, L. orientalis Fisher, L. avicularia Fisher, L. longispina Sladen and L. hardwicki Gray) from Chinese waters; and Clade C including L. maculata Müller & Troschel from Chinese waters. Our molecular phylogeny results support the morphological Quinaria-Group and Alternata-Group assigned by Döderlein. Seven nominal species we sampled do not exhibit genetic distances that are large enough to recognize them as separate species. Cryptic species may exist in’ Luidia quinaria’ from the Yellow Sea and the Sea of Japan. Meaningful morphological characters need further investigation in Luidia.  相似文献   

13.
军曹鱼全人工繁殖群体遗传特征的SSR分析   总被引:1,自引:1,他引:1  
利用8个微卫星DNA位点分析南海海域5个军曹鱼全人工繁育群体(HN1、HN2、ZJ、FJ和LS)子代的遗传多样性特征和群体间遗传分化。结果显示,军曹鱼养殖群体与天然群体的遗传结构特征基本一致:1)平均有效等位基因数为3.910±0.440,观测杂合度为0.595±0.049,分子方差分析(AMOVA)表明,个体内分化占主导(46%),军曹鱼养殖群体整体遗传多样性较高;2)群体间基因流明显(N_m=2.5959,F_(st)=0.0878),整体分化程度较低。各养殖群体表现出不同于天然大群体的特征:1)绝大部分位点均明显偏离哈温平衡,杂合子缺失或过剩现象普遍存在;2)聚类和群体分配分析等表明HN2与另四个养殖群体(HN1、ZJ、FJ和LS)分化明显。  相似文献   

14.
云南洞穴金线鲃属鱼类(鲤科)一新种   总被引:1,自引:0,他引:1  
描记采于罗平县—地下河金线鲃属一新种,命名为瓦状角金线鲃Sinocyclocheilus tileihornesMao,Lu et Li,sp.nov。新种外形与犀角金线鲃S.rhinocerous Li et Tao(1994)相近,但新种无侧线鳞,角顶部分叉呈瓦状,腹鳍较长,后伸超过肛门或达到臀鳍起点可与之相区分。  相似文献   

15.
描记采于云南省沪西县城郊龙潭及阿庐古洞的金线鲃属一新种,命名为阿庐金线鲃Sinocyclocheilus aluensisL ietX iao sp.nov。新种在外形上与狭孔金线鲃S.angustiporusZhengetX iao(1985)相近,但有下列特征与之区别:1)新种头长显著大于体高;后者头长约等于体高。2)新种背鳍起点至吻端的距离大于至尾鳍基的距离;后者正相反。3)新种鳃孔大,上角超过眼上缘水平线;后者鳃孔小,上角低于眼上缘水平线。4)经线粒体细胞色素b基因测定,两者分子遗传距离为3.0%,提示是两个独立种。  相似文献   

16.
The problem of wild elephants, or human-elephant conflict (HEC), influences the daily life of local communities and hinders the conservation of wild elephants.The perception and attitudes of local communities who inhabited the frontiers between human activities and wild elephant movement are important to the mitigation of the HEC and conservation of wild elephants. To analyze the perception and attitudes of local communities, the Participatory Rural Appraisal (PRA) was used in the investigation of 423 interviewees from 22 villages in Xishuangbanna from July 2009 to February 2010. The results indicated that local communities had their views on the elephant-related problems. In field survey, we found that 66.5% of interviewees were willing to support, participate in, and assist in the conservation of wild elephants;33.5% of interviewees were opposed or indifferent to such conservation, because their livelihoods and even their lives were endangered by wild elephants. These views and attitudes were influenced by local communities′perception of HEC, education level, gender and self-interest. Therefore, it is necessary to analyze the diverse views among local communities and balance profits and costs in addressing HEC.  相似文献   

17.
Specimens of a new species of Cerithiidae, Cerithium mangrovum n. sp., were collected during two surveys along the coasts of Hainan and Guangdong Province, China. Usually associated with potamidid snails, this species often occurs in large populations between the mid-high tidal zones in a range of habitats, including mangroves, grass beds, silt, mud, and coral reefs. C. mangrovum n. sp. has a slender and tapering shell and the straight-sided whorl bears three aligned beaded spiral cords. The thick outer lip has a wide posterior sinus. It morphologically resembles C. coralium Kiener, 1841. The shell of C. coralium is usually larger and wider and the spiral cords are not as beaded as in C, mangrovum n. sp. Its radula has a rachidian tooth with a shallow, wide, median basal projection while the rachidian tooth of C. mangrovum n. sp. has a moderately long, median basal projection.  相似文献   

18.
描记采于云南省邱北县一地下洞穴盲金线鲃一新种,以其头上骨质突形状如鹰喙命名鹰喙角金线鲃Sinocyclocheilus aquihornes sp.nov.。新种头形及完全退化的眼与分布于云南泸西阿庐古洞的透明金线鲃S.hyalinus Chen et Yang(1994)相近,但有下列特征可区别:1)角形如鹰喙,后者为一向前的直突起;2)侧线完全,侧线鳞为36,后者侧线不完全,侧线鳞孔9-11;3)背鳍起点位于体中点,至吻端的距离等于至尾鳍基的距离;后者背鳍起点位于体中点之后,至吻端的距离大于至尾鳍基的距离。  相似文献   

19.
One of the fundamental questions in community ecology is whether communities are random or formed by deterministic mechanisms. Although many efforts have been made to verify non-randomness in community structure, little is known with regard to co-occurrence patterns in above-ground and below-ground communities. In this paper, we used a null model to test non-randomness in the structure of the above-ground and below-ground mite communities in farmland of the Sanjiang Plain, Northeast China. Then, we used four tests for non-randomness to recognize species pairs that would be demonstrated as significantly aggregated or segregated co-occurrences of the above-ground and below-ground mite communities. The pattern of the above-ground mite commu- nity was significantly non-random in October, suggesting species segregation and hence interspecific competition. Additionally, species co-occurrence patterns did not differ from randomness in the above-ground mite community in August or in below-ground mite com- munities in August and October. Only one significant species pair was detected in the above-ground mite community in August, while no significant species pairs were recognized in the above-ground mite community in October or in the below-ground mite communities in August and October. The results indicate that non-randomness and significant species pairs may not be the general rule in the above-ground and below-ground mite communities in farmland of the Sanjiang Plain at the fine scale.  相似文献   

20.
INTRODUCTIONPhytoplaktonhasakeyroleinthemarineecosystemasthebasicpartinthefoodchain ,whichisimportantinformationforassessingproductivitypotentialandfisheryresources.Phytoplanktonalsohasanimportantroleinthecarbonbiogeochemicalcycle,becauseitcanabsorbala…  相似文献   

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