Diel changes in bacterial biomass and growth rates in coastal environments, determined by means of thymidine incorporation into DNA, frequency of dividing cells (FDC), and microautoradiography

Abstract

During 4 diel cycles in a Danish coastal environment, bacterial growth rates were estimated by several methods. super(3)H-thymidine incorporation into DNA gave results of the same order of magnitude as data obtained from frequency of dividing cells (FDC). In contrast to minor diel changes in cell numbers and bacterial secondary production, marked diel changes were observed in the percentage of active bacteria determined from microautoradiography using super(3)H-thymidine. Between 20 and 80% of the bacteria were active.