ABSTRACT
Sedimentation is usually overlooked as a loss factor for bacteria in planktonic environments due to the extremely low sinking rates predicted by theory for organisms of their size range. In general, whenever bacteria are found in particles many times their individual size, they will experience significant losses by sedimentation. Sediment traps allow quantification of the number of bacteria that sediment out of the water column during a certain period of time. The water column can be divided into two compartments separated by the mouth of the trap. What is measured is the flux of bacteria from the upper to the lower compartment across the sedimentation boundary. Decomposition of bacteria inside the trap, grazing by predatory organisms, or even growth of bacteria inside the trap are factors to be taken into account. The interpretation given to this sedimentary flux depends, to a great extent, on the characteristics of the upper compartment.
