Seasonal variation of two different heterotrophic bacterial assemblages insubarctic coastal seawater

The numbers of heterotrophic bacteria in the subarctic coastal seawater of Funka Bay, Japan, were measured by now cytometry, and 2 different bacterial assemblages were detected: cells with low DNA content (Group I) and cells with high DNA content (Group II). Although the abundances of both Group I a nd Group II bacteria showed similar regression slopes against seawater temp erature (p < 0.7), Group II bacteria consisted of high growth capacity cell s, growing actively in an enriched incubation experiment, whereas Group I b acteria consisted of inactive cells, not responding to an enriched environm ent. The seasonal variation of the total bacterial abundance observed in Fu nka Bay was caused almost exclusively by Group II bacteria.