| Phytoplankton predominated in the marine concerning their abundance. They playan important role in material circulation and energy flow in the marine ecosystem.Their diversity of species is rich and they are the key contributors of material primaryproductivity. During the5th Chinese Arctic Research Expedition in summer2012, weanalyze the photosynthetic pigments from Norwegian and Greenland Seas, ChukchiSea, and Bering Sea by HPLC. Contributions of different phytoplankton assemblagesto chlorophyll a were obtained by Chemical Taxonomy (CHEMTAX), and thusresulted in composition of the phytoplankton community structure.We analyzed the photosynthetic pigments from different stations of two sectionsfrom Norwegian and Greenland Seas, to get community structure at the surface andsubsurface water (about30m depth). The result showed that average concentration ofchlorophyll a at surface water was23.59ng/L, lower than that at upper water(30.38ng/L). The contributions of phytoplankton to chlorophyll a were nano-> micro->pico-one. Prasinoxanthin, Fucoxanthin, Alloxanthoxyletin, Peridinin, Zeaxanthin,19·-but-fucoxanthin,19·-hexanoyloxyfucoxanthin were observed in the waters. Theirdistributions were relative to environmental factors, including nutrients, temperatureand salinity. The composition of phytoplankton showed that Haptophytes-S(28%),Haptophytes-N(21%), Diatoms(18%), and Prasinophytes (12%) were mainassemblages in the picoplankton; the main composition of nanophytoplankton wereHaptophytes-S(53%), Haptophytes-N(20%), and Diatoms(12%); meanwhile, Diatoms(63%) dominated the microphytoplankton, followed by Dinoflagellates(17%).We analyzed the photosynthetic pigments from Chukchi Sea by HPLC, combinedwith environmental factors, got the correlation between the pigments concentration andenvironmental factor. Contributions of different phytoplankton of every level to chlorophyll a were obtained by Chemical Taxonomy (CHEMTAX), and thus resultedin composition of the phytoplankton community structure at the surface and upperwater. The results showed that: There were plenty of Chl a and Fuco in Chukchi Sea,and some Chl b, Prasino, Peri,19·HF,19·BF, Zea, Allo were discovered too, theseshowed that there are various kinds of phytoplankton. At both surface and subsurface,diatoms had obvious advantage in microphytoplankton, nanophytoplankton andpicophytoplankton, and the ratios of subsurface were higher than the surface·s. Therewere some Chlorophytes and Haptophytes in the nanophytoplankton; Prasinophytesand Cyanobacteria occupied a certain proportion in picophytoplankton. Concentrationof pigments had a obvious relationship with environmental factors, Chukchi Sea wasunder control by hydrographic factors and nutrients, pigments of the stations are rich，which had higher salinity and nutrients, and lower temperature. Concentration ofpigments were higher at subsurface than at surface.We analyzed Chl a and the photosynthetic pigments of different stations fromBering Sea by HPLC, with the environmental factors data, to get community structureat the subsurface water (about30m depth). The result showed that the concentration ofChl a at subsurface was307.05ng/L. Nanophytoplankton was the primary contributorof biomass of phytoplankton, the second one was Microphytoplankton, the last onewas picophytoplankton. Size-fractioned Chl a had a certain relationship withenvironmental factors，it had a negative relationship with temperature and salinity,while, had a positive relationship with nutrients(NO3-, NO2-, SiO3-), had littlerelationship with PO43-. Diatom had a positive dominate position in picophytoplankton,nanophytoplankton and microphytoplankton, its contribution to Chl a, respectively,50.8%,77.1%,90.4%. Prasinophytes had an obvious advantage in picophytoplankton,its contribution to Chl a was17%. Some stations (BN04and BL15) had muchHaptophytes-S and Haptophytes-N. The contribution of Cryptophytes·s tonano-fractioned Chl a was8.5%. The contribution of Diatom to microphytoplanktonwas biggest than other class groups. |
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