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

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 curta is 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:open-water, 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 curta is 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.