Seasonal changes in heterotrophic bacteria under fast ice near Syowa station, Antarctica

Abstract

Seasonal changes in the number of heterotrophic bacteria and the species composition of their communities were investigated in the fast ice area of Syowa station (69°00′S, 39°35′E), from May 1983 to January 1984. Numbers of heterotrophic bacteria under the fast ice began to increase in October and the maximum number of colony-forming units/mL (2.4 × 102) were obtained in late December. The changes in bacterial numbers coincided well with those of particulate organic carbon, suggesting that the growth of heterotrophic bacteria depends on the supply of particulate organic carbon from ice algal assemblages which grow rapidly at the bottom of sea ice during the austral spring. Vibrionaceans in the communities in September accounted for as much as 35% of the isolates, whereas in December, they were not detected at all. These results indicate that there is a seasonal succession in the bacterial communities between September and December.Key words: heterotrophic bacteria, vibrionaceans, fast ice, Antarctica.