ABSTRACT: To determine the relationship between phytoplankton and bacteria biomass near the ice-water interface in the Antartic, the seasonal distributions of phytoplankton and bacteria populations were investigated on the continental shelf of Terre Adélie during the ice coverage period. An under-ice surface station was sampled weekly from March 1991 to January 1992 for the bottom ice and for surface, 0.5 and 2 m depth seawater. Seawaterchlorophyll a values ranged from 0.9 mg m^-3 in summer to 0.01 mg m^-3 in winter. Values 50 times higher were recorded in the overlying ice. Bacterial abundance ranged from 0.5 x 10¹¹ cells m^-3 in July to 6.0 x 10¹¹ cells m^-3 after the ice break-up. Values reaching up to 2.5 x 10¹² cells m^-3 were recorded in sea ice. Bacterial biomass and chlorophyll a concentrations were significantly correlated in both sea ice and underlying seawater. Bacterial biomass represents between 1 and 10% of total microbialbiomass in sea ice and from 10% (summer) to up to 90% (winter) of the living community in the underlying seawater.

KEY WORDS: Phytoplankton . Bacterioplankton . POC . Seasonal variations . Sea ice . Antarctica

Published in MEPS Vol. 123 (1995) on July 20
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1995