白令海特征区域的表层沉积硅藻分布及其古海洋学意义

The distribution of diatom species from surface sediments of characteristic regions in the Bering Sea and their paleoceanographical significance

对白令海表层沉积物样品进行硅藻分析,共鉴定硅藻30属56种(含变种),并确定17种硅藻新记录,其中包括Kisseieviella carina等3种化石种。白令海表层沉积物中的硅藻优势种为Neo-denticula seminae,Fragilariopsis cylindrus和Fragilariopsis oceanica,在白令海北部陆坡深水区附近以Neodenticula seminae为主,而在白令海北部陆架以Fragilariopsis cylindrus和Fragilar-iopsis oceanica为主。对硅藻结果进行聚类分析,可以划分出3个硅藻组合,硅藻组合Ⅰ代表海冰种硅藻组合,组合Ⅱ代表受阿拉斯加流影响的大洋浮游硅藻组合,组合Ⅲ代表上述两个硅藻组合之间的过渡组合。Fossula arctica是17种硅藻新记录之一,首次记录于白令海表层沉积物中,其百分含量分布趋势与Fragilariopsis cylindrus和Fragilariopsis oceanica的相近,在白令海北部陆架为11.7%～17.1%,而在陆坡深水区附近明显减少,是继Fragilariopsis cylindrus和Fragilar-iopsis oceanica之后白令海又一海冰指示种,并有望成为一种有效的海冰变化替代物运用于晚第四纪以来白令海海冰进退历史研究。

Diatom analyses were conducted on 13 surface sediment samples from the Bering Sea. A total of 56 species and varieties belonging to 30 genera were identified, among which 17 ones were documented from the Bering Sea for the first time, including three fossil taxa such as Kisseieviella carina. The domi- nant species were Neodenticula serninae , Fragilariopsis cylindrus and Fragilariopsis oceanica , with N. seminae dominated the vicinity of continental slope and the other two species dominated the northern conti- nental shelf respectively. According to the results of cluster analysis, three diatom assemblages could be distinguished from the Bering Sea, which represented a sea-ice diatom assemblage, a pelagic planktonic di- atom assemblage under strong influence of the Alaskan Stream and a transitional diatom assem- blage. Fossula arctica is one of the 17 new records of diatom species from the Bering Sea with a distributional trend similar to that of F. cylindrus and F. oceanica, which amounts to 11.7%-17.1% on the northern continental shelf and sharply decreases on the adjacent parts of northern continental slope, so it is presumed to be another effective indicator of sea-ice variation other than F. cylindrus and F. oceanica, which can hopefully play an important role in study of late Quaternary sea-ice history in the Bering Sea.