Estimation ofEscherichia coli mortality in seawater by the decrease in(3)H-label and electron transport system activity.

The mortality ofEscherichia coli in seawater was assessed by viable counts, electron transport system activity, and cellular(3)H-labelling. Filtration was used to assess the grazing mortality. Cellular radiolabelling and electron transport system activity were useful methods for assessingE. coli survival in seawater. The decrease in the(3)H-label as a method to assess bacterial mortality was validated by using viable counts and metabolic activity assays. The particulate fraction that passed 2 μm but was retained on 0.2 μm pore-size filters was the primary reason forE. coli mortality in seawater.