Studies on short-term variations of heterotrophic activity in the Kiel Fjord

In summer, 1973, a short-term study with frequent sampling was performed in the Kiel Fjord (FRG). Temperature, salinity, number of viable bacteria, maximum uptakevelocity of glucose and acetate, concentrations of chlorophyll a, labile organic substances and ammonia and phosphate were measured. Strong variations in all parameters during short periods of time could be demonstrated. The number of viable bacteria fluctuated between 26x10⁶ and 195x10⁶ bacteria/l. Changes in the maximum uptake-velocity (V _m ) of glucose between 0.23 and 0.85 μg C l^-1 h^-1 and in the V _m of acetate between 0.36 and 2.40 μg C l^-1 h^-1 were recorded. A highly significant correlation between the number of viable bacteria and the maximum uptake-velocity of the two solutes was found. It is assumed that, at least for this area, at certain times the plate counts represent a major part of the active bacteria flora.