| Chemotaxonomy of phytoplankton based on the pigment biomarkers is a quick and exact method to determine the phytoplankton community composition and abundance. A batch of samples can be determined at a short time by this method and it has the advantage of detecting picophytoplankton which can easily be omitted by microscopic method because of its small size. The development and improvement of this method depend on the knowledge of the pigment biomarkers of phytoplankton species from local area. In this paper, the pigment biomarkers of 37 species of phytoplankton isolated from the coast of China were analyzed by high performance liquid chromatography (HPLC). In addition, the variations of pigment biomarkers of three typical species under different light intensities during growth process were also determined. Based on these works, the improved method was applied to study the spatial-temporal variation of phytoplankton community and abundance of the East China Sea.(1)Pigments of eighteen species of diatoms, fifteen species of dinophyceae, three species of raphidophyceae and one species of haptophyceae were determined by HPLC. Pigment profiles, including pigment to chlorophyllαratios, pigment indices, cellular pigment contents and cellular pigment densities were calculated according to the pigment quality and the cell density.(2) Chlorophyll c1 was detected in Prorocentrum micans, Prorocentrum sigmoides and Gonyaulax spinifera which is different from Jeffrey & Wright's classification of dinophyceae. According to these results, a new type of dinophyceae"dinophyceae pigment type 6"was suggested, in which chlorophyllα, peridinin, diadinoxanthin, chlorophyll c2 and chlorophyll c1 are characteristic pigments.(3)The ratios of the peridinin to total chlorophyllαin dinophyceae in this paper were significantly higher than those reported by other researchers. The reason for this still needs further investigation. The cellular pigment concentrations, especially the cellular non-diagnostic pigment concentrations differed a lot among different species. It varied by up to two orders of magnitude among species even within the same class. Cellular pigment densities showed minor differences among different species compared with cellular pigment concentrations.(4)The variation of the pigment profiles of Phaeocystis globosa, Thalassiosira rotula, and Prorocentrum donghaiense isolated from the China's seas with light intensities during the growth process were studied. In general, all the three species showed adaptation to increasing light intensity by decreasing cellular concentration of chlorophyllα, but the variation patterns during growth process were species-specific. The cellular concentrations of chlorophyllαin P. donghaiense and T. rotula increased gradually with time, but the opposite trend was found in P. globosa. Most of the pigment ratios and pigment indices of these three species were nearly constant during growth process and showed small changes at different light intensities. These pigments can be used in the chemotaxonomy of phytoplankton based on pigment biomarkers. While the ratios of photoprotective carotenoids, such as diadinoxanthin, diatoxanthin andβ,β-carotene to total chlorophylls a showed the trend of increasing with the increase of light intensity during growth process. These pigments should be excluded from the use of the chemical taxonomy of phytoplankton based on the pigment biomarker.(5)The spatial-temporal changes of composition and abundance of phytoplankton community and phytoplankton function types in November, 2007 and May, 2009 in the East China Sea were investigated using pigments as a tool. Diatom, dinophyceae, haptophyceae, chlorophyceae, cyanophyceae, prasinophyceae, chrysophyceae, and cryptophyceae were found in most stations. Diatom was found in the majority of phytoplankton community in inshore area, while the cyanophyceae and prochlorophyceae were found in the majority of phytoplankton community in offshore area, especially in Kuroshio. The contribution of the phytoplankton classes to the total chlorophyllαcalculated by CHEMTAX software differed from that of the phytoplankton function types to the total diagnostic pigments calculated by pigment indices. However, the trends from those two methods were consistent. In contrast, the results obtained from the diagnostic pigments differed a lot from those obtained from the microscopy. The number of species of phytoplankton by microscopy was significantly lower than those by diagnostic pigments. The relationship of these two methods was species-specific. There was a significant and positive relationship for diatoms. While for dinophyceae, the relationship was not significant. The main reason was supposed to be the differences of cellular pigment concentrations among different dinophyceae species. The relationship of these two methods for cyanbacteria was significantly negative. The reason still needs a further investigation.
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