The distributions of bacterial numbers and activities were studied bimonthly in 1987, at 3 sites in Lade Paro for elucidating the changes by disturbance of aquatic ecosystem. The total bacterial number was $0.3 imes 10^{5}-13.1 imes ^{5}$ cells/ml. The geterotrophic bacterial number had the variance from $1.9 imes 10^{3}$ CFUs/ml to $3.1 imes 10^{4}$CFUs/ml and the variation trend was similar to that of the total bacterial number. The proportions of alpha-glucosidase or beta-glucosidase releasing bacteria showed temporal changes rather than spatial changes. The proportions of phosphatase releasing bacteria had the maximum values, 22.7-83.0%, in July. The electron transpory system activity revealed the variation from $480{mu}gO_{2}$/l/day to $1696{mu}gO_{2}$/l/day and hagher values at upper stream and in summer. The degradation fraction by phosphatase was 0.4-9.1%/h and increased with temperature. The maximum value of heterotrophic activity was 8.2%/h in summer. Eventhough the distributions of total bacteria and heterotrophic bacteria were affected by the water disturbance but microbial activities and proportions of the specific enzume releasing bacteria were not affected.