普里兹湾及邻近海区表层沉积硅藻分布与环境分析

DISTRIBUTION OF DIATOMS IN SURFACE SEDIMENTS OF PRYDZ BAY AND ADJACENT WATERS,ANTARCTICA

表层沉积物中硅藻的分布及组合特征对于研究相应的海洋环境有着重要的意义。东南极普里兹湾及其附近海域的22站表层沉积物中鉴定出硅藻36种,分属13属,其中Fragilariopsis curta在普里兹湾内占36.76%~66.36%,Fragilariopsis kerguelensis在湾外开阔水域占54.33%~70.95%。除趋势对应分析（DCA）显示研究区主要的10种硅藻分为开放水域种组合、近海冰种组合和海冰种组合,其表层沉积硅藻组合分布也分成3个区。作为硅藻极地开放海洋指示种的Fragilariopsis kerguelensis分布在普里兹湾外的深海平原,受湾内冰架水的限制,不能向湾内扩散;作为硅藻海冰指示种的Fragilariopsis curta主要分布在普里兹湾内的陆架上,受南极表层水和海冰的影响较重,在湾外受深水溶解作用而急剧减少;作为硅藻近海冰指示种的Thalassiosira antarctica的出现是受普里兹环流、冰架水和海冰的控制。研究区硅藻的组成和分布反映和验证了区域内环流的分布和扩散极限。

The assemblage and distribution pattern of diatoms in surface sediments are of great significance for studying the correspondent marine environment.36 species of diatom,belonging to 13 genera,have been identified from 22 sites in the Prydz Bay and adjacent waters,East Antarctica,in which,the percentage content of Fragilariopsis curtais up to 36.76%~66.36%in the samples from the Prydz Bay and that of Fragilariopsis kerguelensis 54.33%~70.95%in the areas out the bay.Using Detrended Correspondence Analysis（DCA）,the 10 common and dominant species can be grouped into three assemblages：openwater,ice-edge and sea-ice assemblages.Correspondingly the distribution of the diatom assemblages in the surface sediment could be divided into three zones in the study area.Fragilariopsis kerguelensis,the indicator of open-water environment,is mainly distributed in the abyssal plain outside of the Prydz Bay,and can not spread to the bay shelf as the restriction of the Shelf Water.As the representative of the sea-ice diatom,Fragilariopsis curtais primarily distributed on the shelf of the Prydz Bay and is mainly effected by Antarctic Surface Water and sea ice.Inversely,its content decreases sharply in the deep sea due to the increasing in dissolution.Appearing of Thalassiosira Antarctica,the indicator of ice-edge diatom,is mainly controlled by the Prydz Gyre,Ice Shelf Water and sea ice.The composition and distribution of the diatom reflect and confirm the distribution and diffusion limit of circulation current in the study area.