2014年4月10日至5月13日在东印度洋赤道区及其邻近海域（10．08°N—6．00°S，80．00°～96．10°E）进行硅藻物种组成和群落结构的调查。分析了45个网采样品，共鉴定出浮游硅藻34属113种（包括变种、变形及未定名种），大部分物种为热带外洋性种以及暖海外洋性种，与该海区的热带及亚热带的环境特征一致。优势种为佛氏梯形藻（Climacodium frauenfeldianum）、地中海细柱藻（Lep-tocylindrus mediterraneus ）、密聚角毛藻（Chaetoceros coarctatus ）、美丽漂流藻（Planktoniella foromsa ）、大西洋角毛藻那不勒斯变种（Chaetoceros atlanticus var．neapolitanus）、距端假管藻（Pseudosolenia cal-car-avis ，即距端根管藻 Rhizosolenia calcaravis ）、圆柱几内亚藻（Guinardia cylindrus ）、达蒂角毛藻（Chaetoceros dadayi ）、伏氏海线藻（Thalassionema frauenfeldii ）、离心列海链藻（Thalassiosira excen-trica ）、瘤面角毛藻（Chaetoceros bacteriastroides ）以及笔尖根管藻粗径变种（Rhizosolenia styliformis var．latissima）等。硅藻的平均细胞丰度为1．855×103个／m3，其平面分布不均匀，赤道断面细胞丰度较低，高值区出现在海区北部。聚类分析发现有7种生态类群，这些硅藻的种类和丰度平面分布与上层水体（200 m 以浅）温度、盐度及营养盐的水柱平均值有较好的对应关系。%Phytoplankton net samples were collected from 45 grid stations (10.08°N—6.00°S,80.00°—96.10°E) from April 10 to May 13,2014 in eastern Indian Ocean,diatoms including 34 genera and 113 species (including va-riety,form and unidentified taxa)were found in the survey area.Over half species were tropical oceanic species and warm oceanic species,which was in line with the tropical and subtropical environmental characteristics in the survey area.The dominant species included Climacodium frauenfeldianum ,Leptocylindrus mediterraneus ,Chaetoceros coarctatus ,Planktoniella foromsa ,Chaetoceros atlanticus var.neapolitanus,Pseudosolenia calcar-avis ,Guinardia cylindrus ,Chaetoceros dadayi ,Thalassionema frauenfeldii ,Thalassiosira excentrica ,Chaetoceros bacteriastroides , Rhizosolenia styliformis var.latissima.The average cell abundance of diatoms was 1.855 ×103 cells/m3 .The horizontal distribution of diatoms was asymmetrical,the cell abundance was low in the equatorial section,and the northern area was the high abundance zone.Seven groups were divided through the cluster analysis,the species composition and horizontal distribution of diatoms had a good correlation with the integrated average temperature, salinity and nutrients above 200 m.
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