Studies On Ultraplankton Diversity In Subtropical Coastal Waters Of China Seas

Photosynthetic pigments analysis and molecular techniques including ARDRA and DGGE for analyzing small subunit ribosomal RNA(SSU rRNA or 18S rRNA) gene were applied to study temporal and spatial distributions of pigment composition and genetic diversity of ultra-plankton community in subtropical waters of China Seas, including the upwelling regions of southern Taiwan Strait(July, 2004), the entrance of Pearl River(Feb, 2004), the continental shelf along northern South China Sea(Feb, 2004 and July, 2004), and Xiamen Bay (Mar, 2003; May, 2003; Aug, 2003; Dec, 2003; Feb, 2004; May, 2004; Sept, 2004). Main conclusions are as the following : The southern Taiwan Strait, Indicated by diagnostic pigments, ultraphytoplankton groups responded to upwelling events by different distribution patterns. Most significant changes on vertical distribution were that the proportion of Cyanobacteria to total CHLA biomass decreased with depth, while Bacillariophyta, Prasinophyceae or Haptophyta increased with depth . Most of groups were significantly positive correlated to nutrients, suggesting that those groups are likely to be stimulated by nutrients coupled by upwelling,while Cyanobacteria and Prochlorophyta were negative correlated to nutrients.Four 18S rDNA libraries for eukaryotic ultraplankton in the southern Taiwan Strait were constructed. Sequences which were similar to NA and Dinophyceae were very abundant. Certain sequences which were similar to smallest eukaryote, Ostreococcus sp., were an important component in screened clones. Clustering and NMDS analysis revealed that vertical variations among most stations were lower than that between stations. Amounts of OTUs provided indicators for different water masses, such as upwelling.Xiamen Bay Indicated by diagnostic pigments, Bacillariophyta, Prasinophyceae, Cryptophyta and Chlorophyceae were dominant groups of ultraphytoplankton, while Prochlorophyta was not detected all time. Community structure was kept stable in same cruise, however, seasonal variations were prominent. Average CHLA concentration in February of 2004 was lowest, with community structure dominated by Bacillariophyta, Cryptophyta and Prasinophyceae. The highest CHLA concentration appeared in August of 2003, while Bacillariophyta were only dominating groups. In cold season, temperature and salinity determined the distributions of ultraphytoplanktons, while in warm season, Prasinophyceae were...