白令海和楚科奇海表层沉积硅藻分布特征

THE DISTRIBUTION OF SURFACE SEDIMENT DIATOMS IN THE BERING SEA AND CHUKCHI SEA

对中国第二次和第三次北极科学考察在白令海和楚科奇海获取的部分表层沉积物样品进行了详细的硅藻分析,旨在了解白令海和楚科奇海表层沉积硅藻的主要分布情况。研究发现海冰对北极硅藻有着显著的影响,在最小冰边缘线以北海域,由于常年被海冰覆盖,表层沉积物中的硅藻数量极少甚至缺失,而在此范围以南海域,硅藻含量则甚为丰富。白令海和楚科奇海表层沉积物中最主要的硅藻种类及组合有:角毛藻休眠孢子(Chaetoceros restingspores)、海冰硅藻组合(以Fragilariopsis oceanica和Fragilariopsis cylindrus为代表)、极地硅藻组合(优势种有Bacterosi-ra bathyomphla,Thalassiosira antarctic v.borealis及其休眠孢子)、沿岸底栖硅藻组合(主要有Paralia sulcata和Delphe-neis surirella)、诺氏海链藻(Thalassiosira nordenskioeldii)和塞米新细齿藻(Neodenticula seminae)等。上述硅藻种类及组合具有显著的空间分布差异性,并与现代海洋环境因素密切相关,因此对于白令海和楚科奇海古海洋环境研究具有重要意义。

Diatoms from surface sediment samples in the Bering Sea and Chukchi Sea were analyzed to reveal the distribution pattern of the surface sediment diatoms and their relationship with the ocean environment.Diatom was found to be absent in sediment samples from north of the Arctic Sea Ice Minimum,showing the growth and reproduction of diatoms are strongly inhibited by sea ice.In areas between the Arctic Sea Ice Minimum and Maximum,i.e.areas influenced by seasonally changed sea ice,the sea ice diatoms（mainly Fragilariopsis oceanica and Fragilariopsis cylindrus） was found to be the dominant diatom species.Arctic sea ice was therefore confirmed to be an important influencing factor for surface sediment diatoms in the Bering and Chukchi Seas.The Chaetoceros resting spores were more abundant in the Chukchi Sea than the Bering Sea,which was coincident with the composition of modern phytoplankton in these areas,and can possibly be attributed to stronger hydrodynamic condition in the Bering Sea.This species was least abundant on the northeast Bering shelf,possibly because of the lower water depth,stronger effect of the coastal current and river influx,relatively coarser sediment particles,and relatively strong wind and bottom current.The Arctic diatom group（dominated by Bacterosira bathyomphala,Thalassiosira antarctic v.borealis and Thalassiosira antarctic resting spore） was more abundant in the Bering basin and the central and north Chukchi Sea,while the coastal benthic diatom group（including Paralia sulcata and Delpheneis surirella） was mainly found on the northeast Bering Shelf and near Cape Lisburne in the Chukchi Sea.Thalassisira nordenskioledii was most plentiful nearby the Bering Strait,and Neodenticula saminae was only found in the Bering Sea,especially in the Bering basin,indicating close correlation with the Pacific waters.