Article révisé par les pairs
Résumé : A method proposed for estimating the rate of bacterial mortality in aquatic environments consists in following the disappearance of radioactive tracer from the macromolecular fraction of 3H-thymidine labeled natural assemblages of bacteria. The data presented in this paper offer a further technical validation of this procedure. Application of the method to North and Mediterranean Sea, estuaries, rivers and lakes yields first order mortality constant in the range 0.008–0.06 h−1. Mortality due to grazing by protozoans retained by 2 μm filtration range from 20 to 90% of the mortality detected by the method.