Abstract:

During the austral summer of 1989/1990,cell size-fractionated biomass and productivity of phytoplankton,particulate organic carbon(POC) and the relevant environmental parameters in the surface of a large scale sea area encircling the Antarctic continent were observed.The results showed that,in the Antarctic waters,the Southern Atlantic Ocean is the most fertile,chlorophyll a concentration averaged over 2 μg/dm 3;average POC concentration was also the highest (>100μg/dm 3),while being lower in the Drake Passage and the Southern Indian Ocean.The results of size-fractionated chlorophyll a showed that netplankton with cell >20μm in the Southern Atlantic Ocean having abundant nutrients accounted for the highest proportion(65%),while in infertile Southern Indian Ocean,picoplankton accounted for the highest proportion,for example,averagely accounting for 47% in the Southern Indian Ocean.The results of size-fractionated productivity showed that the contribution of picoplankton to total productivity was the largest in the Southern Atlantic ocean and Drake Passage,that of nanoplankton and netplankton were approximate.The relative high photosynthesis assimilation number of picoplankton menifests their importance in marine ecosystems of the Antarctic water.In comparison with the Antarctic water,the Subantarctic and Subtropical waters are infertile.