CARBOHYDRATES IN THE NORTH-SEA DURING SPRING BLOOMS OF PHAEOCYSTIS - A SPECIFIC FINGERPRINT

Regional and temporal variation in the composition of water-soluble ca rbohydrates from Phaeocystis colonies sampled in the southern North Se a was small during spring 1994, except for a high variability in the c ontribution of glucose. Glucose is universally present in storage prod ucts of microalgae; the relative constancy of the carbohydrate pattern of the other monosaccharides suggests that these are part of the more refractory colony mucus. In all Phaeocystis samples arabinose dominat ed, followed by xylose (Belgian coast) or galactose and mannose (Dutch coast). Rhamnose, glucuronate and O-methylated sugars were present in lower amounts. The latter, always present in samples containing Phaeo cystis, may be typical for North Sea strains. The sugar patterns we re port here differ from those presented in the literature concerning Pha eocystis-derived material, and also from the sugar fingerprint in the preceding diatom bloom. The Phaeocystis mucus apparently behaves as pa rticulate matter since it was retained on filters of over 1 mu m. This characteristic together with its refractory nature, typical of 'trans parent exopolymer particles' (TEPs), must have consequences for the he terotrophic microbial community in terms of adherence and substrate av ailability.