A dye‐binding assay for the spectrophotometric measurement of transparent exopolymer particles (TEP)

Abstract

Large transparent exopolymer particles (TEP) are found abundantly in the 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 determine the concentration of TEP colorimetrically. In this method TEP are first stained with alcian blue. The dye complexed with TEP is then redissolved and measured spectrophotometrically. Several independent tests of the method show that the concentration of TEP measured spectrophotometrically compares well with parallel light microscope counts. Fractionation experiments confirm that TEP are not generated as an artifact of filtration. Field data show that the concentration of TEP in different oceanic environments ranges from 10 to 500 µ g liter ‒1 xanthan equivalent depending on season, depth, and plankton community composition.