Abstract: In vivo fluorescence has seen wide application in the analysis of microalgae. It has been used to assess phytoplankton biomass, rates of primary production (PP), and physiological status. This paper describes a preliminary investigation of the joint application of the three kinds of fluorescence analysis in the physiological study of microalgae. Flow cytometry (FCM) and fluorescence spectrometry were used to determine the in vivo static fluorescence information of pigments, and a pulsed-amplitude-modulation chlorophyll fluorometer (PAM) was used to determine the dynamic fluorescence of chlorophyll. The validity of the joint application was proven by two laboratory cultured arctic microalgae called Pseudo-nitzschia delicatissima and Thalassiosira sp. The higher value of minimum fluorescence yield in dark-adapted state (Fo), actual photochemical efficiency of PSⅡ (ΦPSⅡ), and electron transport rate (ETR) resulted in a higher cell abundance and chlorophyll a content of P. delicatissima; whereas higher β-carotene content of Thalassiosira sp. played an important role in the protection of photosynthesis.

Key words: Arctic microalgae, flow cytometer, fluorescence spectrum, PAM chlorophyll fluorometer, joint application