The populations, characterization and activity of suspended bacteria in the Welsh River Dee

Abstract

In a 29 month study of bacterial populations at three sites on the Welsh River Dee, the aerobic heterotrophic bacteria increased from an average basal level of about 1.2 times 104 colony‐forming units (cfu)/ml near the source of the river, to 2 times 105 cfu/ml in the lower reaches. The ratio, total bacterial cell count: viable count, decreased from 70 in the upland reaches to 10 in the lower parts of the river. There was no apparent seasonal variation in bacterial numbers but on occasions the bacterial populations in both upland and lowland reaches of the river increased simultaneously. Fluctuations in bacterial numbers over a 50‐fold range were observed in this study. Bacterial isolates from both upland and lowland sites were predominated by two groupings of bacteria, the Pseudomonas—Agrobacterium—Alcaligenes group and the Flavobacterium—Cytophaga—Flexibacter group. Results suggested that the latter group may have been part of the autochthonous population. Seasonal variation in heterotrophic potential (Vmax) for acetate uptake was shown to occur over a 30‐fold range in the lowland reaches of the River Dee. Peaks in activity at the lowland site occurred during the summer months, the range of Vmax values for acetate ranged from 0.2 to 30 μg/1/h. Fluctuations in Vmax values from the upland site were not seasonal but were instead linked to faecal pollution, Vmax values from this site range from 0.04 to 3 μg/1/h.

Seasonal variation in the abundance and heterotrophic activity of suspended bacteria in two lowland rivers

“…and to turnover times for glucose mineralization in the River Hull (Goulder. 1980) and for acetate assimilation in the Welsh River Dee (Nuttall, 1982b).…”

Relationships between bacterioplankton production and limnological variables: Necessity of bacterial size considerations

“…In fact, the evolution of nutrient conditions in lake water during spring and summer, as well as their variations with depth, is inextricably concomitant with the temperature gradient, so this hypothesis may be difficult to test. Nevertheless, the apparent correlation between BP and temperature is, in some cases, not surprising, especially in rivers where an increase in bacterial numbers is often associated with distance downstream (Nuttall 1982). In this case the hypothesis of an indirect relationship is more evident, but the same indirect relationship could prevail in pelagic waters-the temperature being higher in the euphotic zone.…”

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

“…The direct count was about 1/20 lower than that of the deepest part of the three lakes, but the plate count roughly corresponded with the counts at the surface water of the deepest part. It seems that the amount of the plate counts at the inlets is common in the running water of the upper site of the river (Nuttall, 1982;Morikawa, 1984). As shown in Table 2, the plate count at a surface layer (0-1 cm depth) of the sediment at the deepest part was not different among the three lakes and in the range of 7.2-8.9X105 CFU/cm3 of wet sediment.…”