A NEW STAINING TECHNIQUE FOR DUAL IDENTIFICATION OF PLANKTON AND DETRITUS IN SEAWATER

A new method is described that employs dual staining and epifluorescence microscopy for the identification of plankton and detritus in seawater. The staining technique uses the fluorochromes propidium iodide (PI) and 4',6-diamidino-2-phenylindole (DAPI) in conjunction with UV excitation. PII DAPI staining identifies living matter distinct from non-living matter by selectively staining detritus a deep orange color while cells are either blue-white or pink, depending upon stain and cell type. Comparison of this technique with existing epifluorescence techniques and staining reagents indicates that PI/DAPI offers an improved approach for staining detritus and plankton when evaluation of both is desired. This step is a prerequisite for quantitation of the volumes of detritus and plankton. preliminary to independent estimates of their carbon and nitrogen pools in aquatic ecosystems.