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传统的确定岩溶台面的方法是定性的,因而往往有争议,作为台面高程的峰顶面通常并非平坦地面,这也给客观定量地确定台面高程带来困难。本文基于等高线的分形特征,提出根据等高线的分维－高程曲线确定岩溶台面高程。实例研究初步表明,这是一种简便可行的定量方法。 相似文献
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Resting cysts play crucial roles in the ecology of dino?agellates, especially in wintering or surviving unfavorable conditions, seeding harmful algal blooms(HABs), and facilitating the geographic expansion. Encystment of dino?agellates is tightly coupled with sexual reproduction in most cases, which can occur either through homothallism(self-fertilization) or heterothallism(intercrossing of +/-strains). The types of sexual reproduction have important ecological implications. The toxic and HAB-forming dino?agellate, Pheopolykrikoides hartmannii has been previously reported to be heterothallic. Here, we provide visual con?rmation of homothally of P. hartmannii and the ?rst detailed visual recording of cyst germination based on the observations of a clonal isolate from Jiaozhou Bay, China. To document the homothallism, we ?rst observed cell pairs in sexual mating, planozygotes with two longitudinal ?agella, and cysts with typical morphology as described previously from the clonal culture. We then germinated a single cyst, established a new clonal culture from one of the two daughter cells after the ?rst cell division of the germling(i.e. from the diploid germling to two haploid cells), and produced cysts again from the newly established clonal culture. For the observation of the germination time-series, we took micrographs and videos to show all germination processes, particularly with an interesting observation of the short amoeboid stage of the germling releasing from the archeopyle(～15 s), which was a landmark of the germination process and has not been reported elsewhere. This de?nitive evidence of homothallic sexuality and cyst production in P. hartmannii provides a new insight into the biology and ecology of the species, particularly a mechanism that may partly account for the population dynamics and ubiquitous distribution of the species. 相似文献
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Carbonyl compounds,especially polyunsaturated aldehydes(PUAs),are increasingly reported as teratogenic to grazers and deleterious to phytoplankton.While PUAs have been considered to be mainly produced by diatoms after cell wounding,little is known about whether microalgae other than diatoms,particularly harmful algal bloom(HAB)-forming species,produce carbonyl compounds.In this study,we analyzed the carbonyl compounds from eight common HAB-forming species(Akashiwo sanguinea,Karenia mikimotoi,Karlodinium veneficum,Margalefidinium polykrikoides,Prorocentrum donghaiense,P.minimum,Scrippsiella trochoidea,and Heterosig,ma akashiwo)using gas chromatography-mass spectrometry in full scan and selected ion monitoring(SIM)modes.Our results show a ubiquitous presence of carbonyl colmpounds in both dissolved and particulate forms in all species we examined.In the full scan mode,133 chromatographic peaks were detected from 51 samples altogether.Both the varieties of carbonyl compounds and their quantities were algal species dependent,although most of the carbonyl compounds could not be fully identified according to the mass spectral database only due to the unavailability of enough standards for all analytes.Aided with nine standards in SIM mode,we further identified and quantified all nine aldehydes(2-methyl-2-pentenal,trans-2-nonenal,cis-6-nonenal,2,6-dimethyl-5-heptenal,trans-2-hexenal,trans-2-decenal,2,4-heptadienal,trans-trans-2,4-octadienal,and trans-trans-2,4-decadienal).Four of these nine aldehydes were detected in particulate form,which confirmed that trans-2-nonenal could be produced by K.mikimotoi,Karl.veneficum,P.donghaiense,P.minimum,S.trochoidea,and H.akashiwo,2,4-heptadienal and trans-trans-2,4-decadienal by A.sanguinea,M.polykrikoides,and S.trochoidea,and trans,trans-2,4-octadienal by S.trochoidea,respectively.We proved that some dinoflagellate and raphidophyte species could contribute to the pool of carbonyl compounds including PUAs in a marine ecosystem.Some carbonyl compounds,particularly those in high cell quota and/or dissolved concentration,may be related to fishkilling or allelopathy which needs further identification and quantification. 相似文献
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Most of reported harmful algal blooms(HABs)of microalgae(75%)have been caused by dinoflagellates.Studies on the negative effects of HABs have generally focused on animals,valuable organisms in particular,and environmental factors such as dissolved oxygen and nutrients,but relatively fewer on community level,particularly that using metagenomic approach.In this study,we reported an investigation on the effects of a HAB caused by the dinoflagellate Prorocentrum donghaiense on the species diversity and community structure of the dinoflagellate sub-community via a pyrosequencing approach for the samples taken before,during,and after the bloom season of P.donghaiense in the East China Sea.We sequenced partial 28S rRNA gene of dinoflagellates for the field samples and evaluated the species richness and diversity indices of the dinoflagellate community,as a sub-community of the total phytoplankton.We obtained 800185 valid sequences(categorized into 560 operational taxonomic units,OTUs)of dinoflagellates from 50 samples and found that the biodiversity of dinoflagellate community was significantly reduced during the blooming period in comparison to that in pre-and after-blooming periods,as reflected in the four diversity indices:the species richness expressed as the number of OTUs,Chao1 index,Shannon index(evenness),and Gini-Simpson index.These four indices were all found to be negatively correlated to the cell density of the bloom species P.donghaiense.Correlation analyses also revealed that the P.donghaiense cell abundance was correlated negatively with NO3--N,and NO2--N,but positively with total nitrogen(TN)and total phosphorus(TP).Principal coordinates analysis(PCoA)showed that the community structure of dinoflagellates was markedly different among the different sampling periods,while the redundancy analysis(RDA)revealed P.donghaiense abundance,salinity,NO3--N,and SiO32-were the most four significant factors shaping the dinoflagellate community structure.Our results together demonstrated that HABs caused by the dinoflagellate P.donghaiense could strongly impact the aquatic ecosystem on the sub-community level which the blooming species belongs to. 相似文献
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岩溶形态系统的分形特征及其机理探讨 总被引：4，自引：0，他引：4
运用分形理论，系统研究了构成岩溶形态系统的岩溶地貌、水文网和洞穴系统的分形特征，并计算了分维值，以鄂西岩溶区的地貌小区为例，建立了地表峰体的分维与控制岩溶系统发育的岩性，外源水等因素的联系，揭示了分维的岩溶学含义，进而从岩溶系统介质场结构及岩溶作用过程的非线性动力特征分析探讨了岩溶形态系统的分形机理。 相似文献
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Wang Jinxiu Kong Fanzhou Wang Yunfeng Ji Nanjing Song Minjie Hu Zhangxi Niu Zhuang Liu Chao Wang Xin Sun Yuanyuan Yu Rencheng Yan Tian 《中国海洋湖沼学报》2022,40(6):2430-2445
Journal of Oceanology and Limnology - With the development of industrialization and aquaculture in Jiangsu and Shandong Provinces along the South Yellow Sea coast, China, eutrophication has greatly... 相似文献
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Hu Zhangxi Song Xiaoying Wang Jinxiu Tao Zhe Sun Yuanyuan Li Yuhang Liu Yuyang Deng Yunyan Shang Lixia Chai Zhaoyang Tang Yingzhong 《中国海洋湖沼学报》2022,40(6):2292-2311
Journal of Oceanology and Limnology - Many marine dinoflagellates can form resting cysts as a part of their life cycle, and the cysts could be buried in sediment and remained viable for as long as... 相似文献
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The dinoflagellate genus Margalefidinium has been split from Cochlodinium as a new genus recently and Margalefidinium fulvescens is one of the five Margalefidinium species. Margalefidinium fulvescens is toxic and has been reported from the coastal waters of USA, Canada, Mexico, China, Japan, Indonesia, Korea, Pakistan and Spain. Here we provide the morphological and phylogenetic characterization for an isolate of it from the Jiaozhou Bay, Qingdao, China. Our results showed that the vegetative cells were subspherical to ellipsoidal, 34–60 μm in length, and 19–41 μm in width. Both single cell forms and colonies in chains of 2, 4, or 8 cells were observed in cultures, but chain forms with 2 or 4 cells were observed more often in the field samples. The cingulum was rather deep, encircling the cell approximately twice, but the sulcus was rather narrow, surrounding the cell about one turn. The nucleus was spherical and located at the central epicone. The chloroplasts were granular, brownish, and scattered peripherally. An orange pigmented body also appeared in the epicone. The apical groove appeared vase-like as previously described. Under epi-fluorescence microscopy, a pumpkin-like structure was clearly observed, in which cells were embedded. Cells were observed to exit from the structure, which led us to a hypothesis that the structure may provide cells a shelter to avoid predation or to respond to other stresses. The phylogenetic analyses based on partial LSU rDNA sequences indicated that M. fulvescens from the Jiaozhou Bay was grouped with M. fulvescens populations from other origins and closely related to the clade of M. polykrikoides.Our morphological observations and phylogenetic analyses together confirmed the presence of M. fulvescens in China and our monitoring has also observed the species dominant in the dinoflagellate community of the Jiaozhou Bay in the early autumn of 2015, which alerted us to continually monitor this bloom-forming species in the region. 相似文献
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