我国东南近岸海域表层沉积硅藻组合

DIATOM ASSEMBLAGES IN COASTAL SURFACE SEDIMENTS IN SOUTHEAST OF CHINA

对采自我国东南近岸海域18个站位78个表层沉积样品进行了硅藻鉴定分析,根据硅藻优势种和次优势种的分布特征,划分出3个组合和两个亚组合,其较好地对应分布于南海、台湾海峡和东海等3个近岸海域。统计数据表明,近岸海域表层沉积硅藻的分布受大陆入海径流的影响微乎其微,随着水深的增加,我国东南近岸海域海洋初级生产力减小,底栖种、潮间带种减少而浮游种增加;组合Ⅰ的分布表明南海东北部海域明显受黑潮流等外洋水团的影响,可应用组合Ⅱ1和组合Ⅱ2中优势种和特征种硅藻来指示水深,两亚组合面貌的差异是对冬夏两季海峡两侧受不同性质海流控制的响应;组合Ⅲ受沿岸流控制比较明显,而遭受黑潮等外洋水团的影响很弱。

On the basis of diatom analysis for 78 samples from 18 stations in surface sediments collected from coastal waters in southeast China and according to the distribution pattern of dominant and sub-dominant species,three assemblages and two subassemblages of diatoms were divided,corresponding to the three coastal waters of South China Sea,Taiwan Strait and East China Sea respectively.Statistics show that the distribution of diatoms in surface sediments in coastal waters has little relation with continental runoff.As water depth increases,the marine primary productivity decreases.Benthic species and intertidal species decreases while planktonic species increases.The distribution of assemblage Ⅰ shows that the northeastern South China Sea was significantly affected by the Kuroshio Current.The dominant and diagnostic diatom species in assemblages Ⅱ1 and Ⅱ2 can be used to indicate water depth,and their difference is a response to the currents from the two sides of the Taiwan Strait which are different in winter and summer times.The assemblage Ⅲ was obviously controlled by the coastal current with little effect from the Kuroshio current.