Specific growth rate of bacterioplankton, determined at constant temperature, as an indicator of deterioration in water quality

Abstract

The specific growth rate (SGR) of natural populations of bacterioplankton, from three lowland watercourses in the northeastern part of England, was measured at intervals over 15 months using a batch-culture method. SGR of the bacteria from one watercourse showed seasonal periodicity with notably low values (<0.01 h -1 ) in winter which coincided with acid conditions. SGR of bacteria from the other two watercourses, which were permanently circumneutral, showed irregular periodicity and notably low values were never recorded. Thus, SGR is an easily determined indicator which may be used to recognize the inhibition of bacterioplankton, which is brought about by adverse water quality, and which potentially leads to reduction in biopurification capacity.