Bacterial abundance, [H-3]thymidine incorporation rate and heterotrophic nanoflagellate abundance were measured in the water column along transects perpendicular to the Kenyan coast (western Indian Ocean) during June-July (SE monsoon) and November-December (intermonsoon) 1992. Bacterial abundance was low (less than 6 x 10(5) cells ml(-1)). Bacterial production estimated from thymidine incorporation rate at near-coastal stations was higher during the intermonsoon period. Production estimates decreased with depth and distance from the coast. Growth rates of bacteria and heterotrophic nanoflagellate abundance were higher during the intermonsoon, indicating a higher turnover than during the SE monsoon. Grazing rates by nanoflagellates, based on their abundance, were estimated to be 100% or more of bacterial production. Bacteria probably supply only part of the nanoflagellate carbon demand. Bacterial production (BP) was high compared with primary production (PP), with average BPnet/PPnet ratios of much greater than 100% and 34% during the SE monsoon and intermonsoon, respectively. Compared with open oceanic regions, both BP and PP in Kenyan coastal waters are low. We conclude that BP is not directly coupled to PP and that recycled carbon, e.g. via grazing, is an important source for bacterial growth. [KEYWORDS: Heterotrophic bacterioplankton; thymidine incorporation bacterial production; surface waters; microbial loop; food web; dynamics; biomass; growth; sea]
Original languageEnglish
JournalDeep Sea Research Part II-Topical Studies in Oceanography
Journal publication date1997

ID: 378063