A sensitive fluorometric technique for the measurement of phycobilin pigments and its application to the study of marine and freshwater picophytoplankton in oligotrophic environments

A sensitive and specific technique is described for the estimation of playcobiliprotein in freshwater and marine picophytoplankton. The method uses fluorescent properties to detect phycoerythrin concentrations as low as 40 ng L-1 from a 1 L water sample and is capable of distinguishing between R-phycoerythrin, C-phycocyanin and C-phycoerythrin. The application of the method to the study of natural picophytoplankton populations in marine and freshwater environments is described. Nitrate concentrations appear to influence picophytoplankton cellular C-phycoerythrin concentrations in surface waters and increasing cellular C-phycoerythrin fluorescence with water depth suggests that this pigment plays a role as a photosynthetic accessory pigment.