| Chrysophycean stomatocysts are produced by asexual or sexual reproduction of chrysophytes. The stomatocyst wall which is made of silica can be well preserved in nature. They can be used as an important indicator in studies of environmental monitoring, water acidification, climate change, paleoenvironmental evolution, etc. China has a vast territory with diverse topography and climate. Nonetheless chrysophycean stomatocysts have never been specially studied in China. In this thesis, more than1000algae samples collected from the Great Xing'an Mountains were observed by LM.247samples which possessed chrysophycean stomatocysts were observed and photographed by scanning electron microscope (SEM). The morphology of the chrysophycean stomatocysts were studied according to the guidelines of International Statospore Working Group (ISWG)(Cronberg&Sandgren1986), with modifications described by Duff et al.(1995) and Wilkinson et al.(2001); the biological affinities of chrysophycean stomatocysts were also studied. Furthermore, the geographical distribution and ecological characters of the stomatocysts from the wetland in the Great Xing'an Mountains were analyzed. The main results are as follows:1. Totally247samples were observed and photographed by SEM.220morphotypes of chrysophycean stomatocysts were identified, among which160morphotypes are new to science.23morphotypes belong to unornamented stomatocysts lacking a collar;5morphotypes belong to unornamented stomatocysts with a simple cylindrical collar;24morphotypes belong to unornamented stomatocysts with a simple conical collar;19morphotypes belong to unornamented stomatocysts with a simple obconical collar;6morphotypes belong to unornamented stomatocysts with a simple long collar;3morphotypes belong to unornamented stomatocysts with a simple wide collar;7morphotypes belong to unornamented stomatocysts with a true or false complex collar;24morphotypes belong to stomatocysts ornamented with scabrae, verrucae or conula;2morphotypes belong to stomatocysts ornamented with tubercula;53morphotypes belong to stomatocysts ornamented with spines;6morphotypes belong to stomatocysts ornamented with ridges;11morphotypes belong to stomatocysts ornamented with ala;15morphotypes belong to stomatocysts ornamented with ornate or reticulum;7morphotypes belong to stomatocysts ornamented with depressions;1morphotypes belong to stomatocysts ornamented with groove;14morphotypes belong to stomatocysts ornamented with compound ornamentation. Characters of every morphotype as well as the number of specimens, sample number, locality and habitat were described, which were attached with64plates concluding384SEM photos.2. Studied the encystment of Synura pettersenii Korshikov by observing and separating the algae on the spot. Synura petersenii f. bjoerkii and Synura petersenii f. truttae had difference in stomatocysts size and collar morphology, and in habitat. Chrysophycean stomatocysts might be varietate-specific as well as species-specific.3. Six morphotypes of stomatocysts were linked to the chrysophytes which produced them according to the scales remaining on the surface. Cells, scales and stomatocysts of Synura petersenii f. bjoerkii, Synura petersenii f. truttae, Synura sp. nov., Chrysosphaerella longispina Lauterborn emend. Nicholls, Mallomonas eoa Takahashi and Spiniferomonus sp. were described. Chrysophyte species and stomatocysts were identified by SEM micrographs.4. One new species of chrysophyte Synura sp. nov. was observed. This draft new species was very different from the other species in Synura, and its stomatocyst is also a new morphotype. The morphological characters of colony, single cell, scales, and stomatocysts were described by LM and SEM micrographs.5. The geographical distribution and ecological characters of the chrysophycean stomatocysts were analyzed.(1) According to the locality, climate and the waters in the Great Xing'an Mountains, all study sites were classified into seven areas:Aershan, Genhe, Mohe, Tahe, Zhalantun, Jiagedaqi, Hailaer. Aershan had the highest diversity of chrysophycean stomatocyst.199morphotypes were observed in this area, among which142morphotypes are new to science and60morphotypies are endemic.(2) The habitat of the wetland in the Great Xing'an Mountains can be classified into river, stream, spring, lake, lakeshorem, sphagnum mirr, Carex swamp, Carex lasiocarpa wetland, ponds aquatic pond and stone pond. Sphagnum mire and Carex wetland had the most morphotypes.130morphotypes were observed with94and93new morphotypies respectively.(3) The relationship between chrysophycean stomatocyst community and pH, water temperature was analyzed. The effect of pH on stomatocyst distribution was larger than that of water temperature. The stomatocysts from the Great Xing'an Mountains prefer habitat with pH5.5-7.4.214morphotypes, including153new morphotypes, were observed, and105morphotypes were only found in this value. Most stomatocysts were widely distributed in0-25℃...
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