广西钦州湾外湾表层沉积硅藻分布特征

本文对钦州湾外湾54个表层沉积物中硅藻进行分析,鉴定出硅藻153种,分属50属。其中Thalassionema nitzschioides是本区域内最为丰富的硅藻种类。对应分析结果表明,钦州湾表层沉积硅藻分布主要受到海水盐度的影响,其中淡水硅藻Achnanthes delicatula、A.hauckiana、A.levanderi和Cocconeis disculus可以作为低盐度海水环境的指示种,半咸水种Cyclotella striata/C.stylorum、Paralia sulcata与海洋中硅藻Thalassionema frauenfeldii、T.nitzschioides则可以很好的指示高盐度环境。钦州湾外湾54个表层沉积站位可划分为3个硅藻分布区,分别对应高低不同的海水盐度,与实际站位地理分布基本一致。

Distribution of the surface sediment diatoms in the outer bay of Qinzhou bay of Guangxi

Fifty-four surface diatom sediments obtained from the outer bay of Qinzhou bay were examined. A total of 153 species that belonged to 50 genera were identified. Thalassionema nitzschioides was the most abundant species. A unimodal method of correspondence analysis was conducted. The results revealed that the diatom assemblage was mainly affected by the seasurface salinity. Fresh water diatoms such as Achnanthes delicatula, A.hauckiana, A.levanderi, and Cocconeis disculus could be used asindices for low sea surface salinity. In contrast, brackish water species such as Cyclotella striata/C. stylorum and Paralia sulcata combined with some marine diatoms such as T. frauenfeldii and T. nitzschioides were good indicators of high sea surface salinity. Three diatom zones, which represented different sea surface salinity, were divided by correspondence analysis and closely mapped to the actual regional distribution of 54 surface diatom sediments studied.