Vertical zonation and community transition of sea-ice diatoms in fast ice and platelet layer, Weddell Sea, Antarctica

Abstract

Changes in the taxonomic composition of diatoms in fast ice as well as in the underlying platelet layer were followed from June to December 1995 in Atka Bay, Antarctica. Four communities were clearly distinguished: (1) an interior community dominated by flagellates in spring; (2) a bottom community dominated by a small form of Fragilariopsis cylindrus; (3) a platelet-ice layer dominated by Amphiprora kufferathii and Thalassionema sp. growing attached to the ice platelets; and (4) an interstitial community dominated by Chaetoceros neglectus growing in the water between the platelets. Species composition distribution and succession in these communities were related to changes in silicate concentration, pore space and ice-formation processes and the ability of some cells to grow attached to ice platelets. The presence of the platelet-layer communities may have implications for palcoglaciology.