Viability of heterotrophic bacteria in the Bay of Marseilles

Marine microorganism activities are commonly assessed by bulk methods and assigned to the total cell count. The presence in significant amounts of ghost, dead, and damaged cells makes such an assignment a non-correct one. A Nucleic Acid Double Staining protocol (NADS) of fresh water bacteria (Barbesti et al., Cytometry 40 (2000) 214-218) has been adapted to resolve viable, damaged and dead cells in marine environments (Gregori et al., Appl. Environ. Microbiol. 67 (2001) 4662-4670). The present paper reports the first in situ application of this approach, conducted in the Bay of Marseilles in winter and spring periods at two sites with contrasted features. (C) 2003 Publie par Editions scientifiques et medicales Elsevier SAS pour l'Academie des sciences.