Bacterioplankton in Lake Biwa : Annual Fluctuations of Bacterial Numbers and Their Possible Relationship with Environmental Variables
1984 Volume 45 Issue 2 Pages 126-133
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1984 Volume 45 Issue 2 Pages 126-133
Annual fluctuations of bacterial numbers were surveyed at four stations in Lake Biwa between 1981-1982. The total count obtained by acridine orange direct microscopic count method changed in the order of 105-106cells per ml at St. Ie (sited in the pelagic area of the north basin), and 106-107cells per ml at three stations in the south basin. The percentage of the viable count to the total count (V/T ratio) ranged from 0.009 to 1.81%, and the ratio tended to be higher in more eutrophic water. Generally, at St. Ie, the vertical profiles of both total and viable counts clearly correlated with those of chlorophyll-a, pH and dissolved O2 (% saturation); however, hypolimnetic O2 depletion had no effect on bacterial numbers. Rank correlation analysis for the samples of epilimnion also showed significant correlations (p<.0005) between bacterial numbers and pH, chlorophyll-a and dissolved O2 (% saturation), but not pheopigments. These results suggest close relationships between phytoplankton and bacteria in Lake Biwa.
