Seasonal Variations in Four Bacterial Size Fractions from a Hypertrophic Pond in Tokyo, Japan

Abstract

The planktonic bacterial populations in the surface water of the hypertrophic Himon-ya Pond were separated into four fractions ( >35 pm, 35-5 pm, 5-1 pm, and < 1 pm) by size fractionation of suspended particles in the water. The seasonal variations in bacterial numbers over a two year period differed for each of the four fractions. The bacterial counts in the >35 pm fraction were mainly dependent on the biomass of Microcystis colonies. Their peaks were observed in summer. I n the 35-5 pm and 5-1 pm fractions, several peaks in bacterial numbers were observed, influenced by the quality and quantity of the particles associated with the bacteria. The bacterial counts in the i 1 pm fraction contributed a high proportion of the total throughout all seasons except summer.

Bacterial Numbers and Floras in the Water and Sediment of Subtropical Lakes Phewa, Begnas and Rupa in Nepal

“…Therefore, the different proportion of particle-attached bacteria between the two lakes might be influenced by the difference in phytoplankton cells or particulate matters as a microhabitat of attached bacteria. In general, the direct and plate counts in the water of Lakes Phewa, Begnas, and Rupa were comparable to those reported in the water of many eutrophic lakes (Coveney et al, 1977;Aizaki et al, 1981;Konda, 1982), but their counts were considerably lower than those in the water of some Japanese hypertrophic ponds (Konda, 1982(Konda, , 1984. The bacterial data in the present study support a diagnosis of trophic status (meso-eutrophic or eutrophic) of these lakes on the basis of data on total nitrogen, total phosphorus, and chlorophyll-a concentrations after Nakanishi et al (1988).…”

“…In natural waters, detritus and dead phytoplankton were attached with numerous bacteria as compared with living phytoplankton (Jones, 1976;Fukami et al, 1981). Therefore, the relative abundance of freeliving and particle-attached bacteria seems to be regulated by the amount of suitable suspended particles for bacterial microhabitat (Konda, 1984(Konda, , 1985Kato, 1985).…”

“…1 living bacteria). Details of the procedure for size fractionation were described previously (Konda, 1984). Direct counts of bacteria in the water sample fixed with formaldehyde at a final concentration of 2.0% (vol./vol.)…”

“…Direct counts of bacteria in the water sample fixed with formaldehyde at a final concentration of 2.0% (vol./vol.) were determined by the acridine orange direct count (AQDC) method with an epifluorescence microscopy according to Hobbie et al (1977), with slight modifications Konda, 1984). Plate counts of aerobic heterotrophic bacteria in the water sample, size-fractionated sample, and sediment sample were determined by the spread plate method.…”

“…Plate counts of aerobic heterotrophic bacteria in the water sample, size-fractionated sample, and sediment sample were determined by the spread plate method. The medium used was the 1/4-PYG agar (pH 7.0) medium (Konda, 1983(Konda, , 1984. It contained 0.5g/l Bacto-peptone (Difco), 0.25g/l Bacto-yeast extract (Difco), 0.125g/l glucose, 15.0g/l powdered agar in distilled water.…”