A DYE-BINDING ASSAY FOR THE SPECTROPHOTOMETRIC MEASUREMENT OF TRANSPARENT EXOPOLYMER PARTICLES (TEP)

Large transparent exopolymer particles (TEP) are found abundantly in t he ocean and play an important role in many fields of marine ecology. Quantification of TEP by light microscopy, however, is labor-intensive and slow. Here we introduce a simple, semiquantitative method to dete rmine the concentration of TEP colorimetrically. In this method TEP ar e first stained with alcian blue. The dye complexed with TEP is then r edissolved and measured spectrophotometrically. Several independent te sts of the method show that the concentration of TEP measured spectrop hotometrically compares well with parallel light microscope counts. Fr actionation experiments confirm that TEP are not generated as an artif act of filtration. Field data show that the concentration of TEP in di fferent oceanic environments ranges from 10 to 500 mu g liter(-1) xant han equivalent depending on season, depth, and plankton community comp osition.