福建三沙湾表层沉积硅藻分布特征及其与环境因子的关系

Distribution characteristics of diatom in surface sediment and its relation with environment factors in Sansha Bay of Fujian

通过对三沙湾24个站位表层沉积物样品进行硅藻分析,共鉴定硅藻31属84种（包括变种和变型）,其中夏季和冬季分别鉴定出31属71种和31属67种,主要属种以中心纲硅藻为主,如爱氏辐环藻（Actinocyclus ehrenbergii）、波状辐裥藻（Actinoptychus undulatus）、横滨盒形藻（Biddulphia grundleri）、中心圆筛藻（Coscinodiscus centralis）等.在生态习性上,底栖海水种占绝对优势.硅藻丰度从湾顶向湾外递减,夏季丰度高于冬季,平均丰度分别为9 003个/g和6477个/g.沉积物粒度分析显示,三沙湾表层沉积物以粉砂质粘土为主,研究表明三沙湾硅藻丰度与平均粒径存在一定相关性,夏季硅藻丰度变化范围为2 104～28 209个/g,粒径范围为5.26～7.36Φ,硅藻丰度与平均粒径变化范围都较大；而冬季硅藻丰度变化在1 929～14 372个/g之间,粒径范围为5.51～6.98Φ,相对夏季其变化较小,论证了水动力是影响硅藻沉积分布的一个重要因素.对影响三沙湾表层沉积硅藻分布的主要环境因子进行探讨,三沙湾表层沉积硅藻主要受潮流、深度和盐度等影响较大.

Diatoms were analyzed from 24 surface sediment samples in Sansha Bay. In total,84 species belonging to 31 genera of diatoms were identified. Among them 71 species belonging to 31 genera collected in summer and 67 species belonging to 31 genera collected in winter were mainly Centricaes. The dominant groups are ctinocyclusehrenbergii,Actinoptychus undulates,Biddulphia grundleri and Coscinodiscus centralis. In view of ecological characters,the diatoms are dominated by marine epipelic species. What＇s more,the abundance of diatom in surface sediments decreased sharply from northern area to the entrance of the bay and the abundance in summer is higher than winter. The average abundance are 9 003 cells / g and 6 477 cells / g,respectively. The sediment grain size analysis shows that the surface sediment grain size are basically Silty clay and the study shows that diatom abundance have a certain correlation with average grain size. Diatom abundance range from 2 104 to 28 209 cells / g,Grain size varies greatly and ranges from 5. 26 to 7. 36Φ in summer. Diatom abundance ranges from 1 929 to 14 372 cells / g in winter. Grain size changes from 5. 51 to 6. 98Φ and it varies less than that in summer indicating that the hydrodynamic force is an important factor influencing the diatom distribution. The main environmental factors are also discussed in the surface sediment diatom distribution and the surface sediment diatom of Sansha Bay is controlled by tidal current,depth and salinity.