Seasonal variation of microalgal assemblages at a fixed station in King George Island, Antarctica, 1996

Abstract

Microalgal assemblages were measured daily from January to December 1996 at a fixed neritic station in Marian Cove, King George Island, Antarctica. The abundance of microalgae and carbon biomass exhibited clear seasonal variation. Annual mean of total microalgal abundance in surface water was 2.43 x 10(4) cells l(-1). Microalgal cell abundance in Marian Cove showed a multi-modal distribution of standing crop during the study period. Microalgae started to bloom in October and increased abruptly during November. More than 45% (avg. 3.5 mg m(-3)) of chl a was present in the 2 months November and December, dominated by microplanktonic diatoms (>20 mum) such as Fragilaria striatula Lyngbye, Licmophora belgicae Peragallo, and Achnanthes groenlandica Grunow. The increase of these diatoms were mainly due to resuspension of benthic microalgae by wind and tidal currents in spring and summer. In contrast, microalgal assemblages in winter were characterized by the dominance of pico- and nanoplanktonic microalgae (<20 mum) such as Phaeocystis antarctica Karsten, Navicula glaciei Van Heurck, and Navicula perminuta Grunow.