PLANKTONIC CILIATES COMMUNITIES IN SUB-ARCTIC WATERS OF KURILO-KAMCHATKA REGION - COMPOSITION, BIOMASS, TROPHIC STRUCTURE

Investigations were carried out in the 22-th cruise of the R/V <<Akademik Mstislav Keldysh>> at 9 station located in the subarctic waters of the North Pacific Ocean. Species composition, numerical abundance and biomass were studied in fresh samples of water without their preliminary concentrating and fixation. Biomass varied in the range of 1,4-17,0 per 1 m2 in the 0-200 m layer. Nanoplankton ciliates formed as much as 66% of the total ciliates number and 12% of total biomass. The main trophic group was represented by phytoplankton feeding ciliates (75-97% of biomass); ciliates feeding on bacteria formed 2-40% of total biomass. The portion of ciliates containing symbiotic chloroplasts did not exceeded 3% of total biomass.