Abstract
A simple and rapid method for microscopic quantification of an abundant class of labile pico- and nano-sized detrital particles (0.2 to 20 mu m), using the fluorochrome stain DAPI, is described. Using an appropriate UV-filter set, examination of DAPI-stained samples revealed not only blue (DNA-containing) but also yellow particulate matter. We showed that DAPI yellow fluorescing particles resembled detritus made from plankton tow material or copepod faecal pellets and were almost exclusively organic, enzyme-degradable matter. Quantification of the total surface area of these particles in the Ligurian Sea (NW Mediterranean) revealed stocks averaging 80 mm(2) l(-1) in surface layer waters. The possible origin and fate of these pico- and nano-sized DAPI Yellow Particles (DYP) are discussed.