Journal of Oceanography, Vol. 54 (No. 2), pp. 179-184, 1998
Motoo Utsumi1, Yukihiro Nojiri1, Nozomi Ytow2 and Humitake Seki2
1National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305, Japan
2Institute of Biological Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305, Japan
(Received 28 September 1996; in revised form 15 November 1997; accepted 26 December 1997)
Abstract: The population dynamics of attached bacteria at the water-sediment interface were studied in a mesotrophic swampy bog, Matsumi-ike, near Tsukuba, Japan. The density of attached bacteria was higher at the sediment boundary layer than in the water column, and low inside the sediment (deeper than 10 mm below the sediment surface) throughout the year. The density of bacteria attached on the glass slide was highest during spring when the source of organic matter in the water column was mainly withered cattail, and gradually decreased toward summer, while the phytoplankton became the dominant source of organic matter in the water column. The epibacterial populations in the water column and at the boundary showed almost the same seasonal fluctuation in attachment and detachment rates. However, bacterial growth rates did not show the same seasonal fluctuation, and annual average growth rates on the glass slides were all lower than that of bacterioplankton (free-living bacteria in water) in the water column.