BACTERIAL ABUNDANCE AND PRODUCTION IN THE CENTRAL AND EASTERN ARABIANSEA

Seasonal and spatial variations in bacterial and picoplankton abundanc es and bacterial production (thymidine incorporation rates) were deter mined in the water column up to 150 m in several stations in the centr al and eastern Arabian Sea. Higher bacterial densities of about 1 x 10 (9) cells L(-1) were observed during the intermonsoon periods of Septe mber and April/May compared to the southwest monsoon period of July/Au gust and the winter period of February/March Although primary producti on was low during April/May, bacterial production was much higher duri ng this period unlike July/August. it also showed an increase from the northern to the southern Arabian Sea, suggesting the presence of high amounts of dissolved organic carbon in this area. High picoplankton d ensities, ranging up to 45 x 10(6) cells L(-1) were observed during Fe bruary, particularly in the northern Arabian Sea. Rapid turnover of ba cteria during the intermonsoon period of April/May suggests the predom inance of a 'microbial loop' in the foodweb and a prevailing source of dissolved organic carbon in the oceanic waters.