EFFECTS OF ENHANCED ULTRAVIOLET-B RADIATION ON THE PRODUCTION OF LIPID, POLYSACCHARIDE AND PROTEIN IN 3 FRESH-WATER ALGAL SPECIES

1. The effects of ultraviolet-B (UVB-enhanced) radiation on the produc tion of photosynthates (Lipid, protein, polysaccharide and low molecul ar weight compounds) was examined for three species of algae. Cryptomo nas sp., Nitzschia palea and Synechococcus elongatus were selected as representatives of the Cryptophyceae, Bacilliarophyceae and Cyanobacte ria, respectively. 2. Laboratory experiments were performed at several UVBweighted dose rates ranging from 0.018 to 0.391 mW cm(-2). These d ose rates span the range of dose rates used in other studies. 3. Effec ts on the overall photosynthetic rate were observed, even at relativel y low UVBweighted dose rates (0.047 mW cm(-2)). 4. The effect of UVB r adiation on the fixation of carbon into the main macromolecular pools differed depending not only on the dosage but on the species examined. However, the observed inhibitory effects were generally non-stochasti c. In addition, within each species there were differences in the appa rent sensitivity of the various fractions to inhibition by UVB radiati on. 5. These results suggest that exposure to UVB radiation has the po tential to alter the relative allocation of recently fixed carbon to l ipid, protein, polysaccharide and low molecular weight compounds in al gae in a species-specific manner.