PLANKTONIC COMMUNITY IN THE PACIFIC SECTO R OF THE ANTARCTIC IN FEBRUARY - MARCH, 1992

The paper is based on the materials from 19 stations taken during the 6th cruise of the RN ''Akademik loffe'' in February - March, 1992, alo ng the sections from the Adelaide Island to the Pennella Coast and nor theastwards of the Balleni Isls. Distribution of some integral estimat es of plankton abundance is considered. Biomass of seston collected in the 0 - 1000 m layer by vertical catches with the Judy net of 176 mum mesh averaged 52.3 +/-6.8 ml/m2, salpa being neglected. In concentrat ions of salpa at 4 stations their biomass was 521 +/- 172 ml/m2. Chlor ophyll in the 0 - 200 m layer determined by fluorescence was 50 +/- 4. 9 mg/m2, biomass of heterotrophic bacteria in the same layer was 5.38 +/- 0.36 g/m2. Quantitative variations of seston and chlorophyll were similar, they did not depend on alternations of the Antarctic water mo difications and were caused by regional and temporal factors. Their ab undance areas are supposedly related to local upwellings, and poor one s - to grazing down by salpa and to the pre-spring seasonal state of t he community. The east to west successive changes of the vertical prof iles of seston recorded along the route were a reflection of phase alt ernations of the annual cycle of plankton. The chlorophyll vertical pr ofiles differed in the number of peaks, their position and confinement to definite elements of hydrophysical structure. No changes of these parameters due to alternations of biological seasons were found. Tempo ral correlation between bacterio- and phytoplankton abundance was not recorded.