通过提取山东半岛北岸不同类型潮间带海水样品的总DNA,构建16S r DNA文库,利用群落相似性分析(ANOSIM)和非度量多维尺度转换排序(NMDS),探究潮间带类型对浮游细菌群落结构的影响,并对比了与近海浮游细菌群落结构的差异。分析结果显示,浮游细菌的丰度及多样性受到潮间带类型的影响,烟台养马岛泥滩、石滩、辛安河沙滩、黄河三角洲碱蓬区和天鹅湖海草区以变形菌门占优势,而黄河三角洲米草区以拟杆菌门为优势菌,其中,天鹅湖海草区浮游细菌的丰富度和多样性最高。潮间带海水中浮游细菌的组成与近海存在显著差异,潮间带浮游细菌的丰度及多样性均显著高于近海。推测季节因素、植被类型、有机质来源可能是造成潮间带不同生境与近海浮游细菌多样性差异的重要因素。
The spatial distribution of siliceous microfossils(diatoms and silicoflagellates) in the surface sediments was mapped at 113 sites in the Yellow Sea and sea areas adjacent to the Changjiang(Yangtze) River,China. In total,267 diatom taxa and two silicoflagellate species were identified from the sediments. The spatial variations in abundance and diversity were classified into three distinct geographic patterns using Q mode clustering: a south-north geographic pattern,a coastal-offshore pattern and a unique pattern in the Changjiang River mouth. The south-north geographic pattern was related to the spatial variations in sea temperature. C oscinodiscus oculatus,a warm-water species,indicated these variations by a gradual decrease in abundance from the south to the north. The coastal-offshore pattern was in response to the spatial variations in salinity. Cyclotella stylorum,Actinocyclus ehrenbergii and Dictyocha messanensis,the dominant brackish species in coastal waters,significantly decreased at the isobaths of approximately 30 m,where the salinity was higher than 31. Paralia sulcata and Podosira stelliger indicated the impact of the Yellow Sea Warm Current in the central Yellow Sea. The unique pattern in the Changjiang River mouth showed the highest species diversity but lower abundance,apparently because: freshwater input can significantly increase the proportion of brackish species; nutrients can supply the growth of phytoplankton; and high sedimentation rates can dilute the microfossil abundance in the sediments. Our results show that an integration of environmental factors(e.g.,nutrient levels,sedimentation rate,sea temperature,salinity and water depth) determined the spatial characteristics of the siliceous microfossils in the surface sediments.
