Abundance Survey On Nano-plankton Of Northern Yellow Sea China In 2007 Spring And Autumn And Isolation And Identification Of Two Marine Nano-diatom

To study the distribution and daily variation of nanoplankton in the northern Yellow Sea, nanoplankton abundance in spring and autumn was determined Nano-plankton Direct Count in the northern Yellow Sea was in the range between 5.01 cells/ml and 91.87 cells/ml at the 78 sampling stations, with a mean of 29.50 cells/ml in spring. Direct Count in the northern Yellow Sea was in the range between 4.70 cells/ml and 151.73 cells/ml at the 80 sampling stations, with a mean of 34.15 cells/ml in autumn. Higher nanoplankton abundance was found at the 10m,20m layers in offshore waters of the Liaodong Peninsular,Shandong Peninsular and the way of Bohai warm current than those in other waters in both seasons. The results show that diatoms and dinoflagellates are the major components of phytoplankton community in the survey region, with cynobacteria, green algae being also common found in some stations.The data of both season showed the similar trend that the diurnal variation of nanoplankton abundance of the surface and the 10m layer was more significant than those of the 30 m and the bottom, while the variation of the abundance of the bottom layer was small. According to multicorrelation analysis, nanoplankton abundance in spring had correlation with the environmental parameters but not significant, while in autumn the abundance had significant positive correlation with the temperature, significant nagitive correlation with the depth, no significant correlation with the salinity. A nanoplanktic strain was isolated from Taiping Corner of Qingdao through limited dilution method on 96 multiwell cell culture plate. It was impossible to distinguish it from Chaetoceros gracilis in light microscope and there were few differences in the structure of flagellum in electronic microscope, so it was prelimin-ary identified as a Chaetoceros species (Chaetoceros sp.qd) based on morphological features.There was a alternative protuberance every 0.5μm on the flagellum whose top liked a wimble, reticular framework presented as helix structure which extended tothe top,there was diaphragm plate that linked the framework and shaped the hole structure. The 18SrDNA sequence was amplified, sequenced to be 1623bp long and had highest level similarity (99%) with strain UTEX LB 2375 of Chaetoceros gracilis retrived from GenBank database. The strain was ascribed to the Chaetoceros genus. The 5.8S rDNA and ITS sequence was further amplified which were 837bp, the BLAST analy-sis showed that Chaetoceros sp.qd had high level similarity with Chaetoceros at 99% in 5.8S region, but there were remarkable differences in ITS region. Phylogenic tree construction and genetic distance analysis indicated that the isolated Chaetoceros sp.qd diverged with other Chaetoceros species, formed a separate branch in the phylo-genic tree. Combined with morphological results, Chaetoceros sp.qd is suggested to be a new species of Chaetoceros.A nanoplanktic strain was isolated from Taiping Corner of Qingdao through limited dilution method on 96 multiwell cell culture plate. It was impossible to distinguish it from Thalassiosira allenii and Thalassiosira hispida in light microscope, in electronic microscope, there are many differences in the quantity of support enation between Thalassiosira sp.qd and Thalassiosira allenii, it also has many discrepancy in the quantity of pore texture between Thalassiosira sp.qd and Thalassiosira hispida, so it was preliminary identified as a Thalassiosira species (Thalassiosira sp.qd) based on morphological features. The 18SrDNA sequence was amplified, sequenced to be 1640bp long and had highest level similarity (98%) with strain UTEX LB 2375 of Thalassiosira angulata strain BEN02-35 retrived from GenBank database. The strain was ascribed to the Thalassiosira genus. The 5.8SrDNA and ITS sequence was further amplified which were 762bp, the BLAST analysis showed that Chaetoceros sp.qd had high level similarity with Thalassiosira at 99% in 5.8S region, but there were remarkable differences in ITS region. Phylogenic tree construction and genetic distance analysis indicated that the isolated Thalassiosira sp.qd diverged with other Thalassiosira species, formed a separate branch in the phylogenic tree, This suggested that Thalassiosira sp.qd was a new specie. However we can't verified the deduction in molecular biology because lack of the 5.8S-ITS sequence. But we provide the detailed data in morphology and molecular biology, so it established the foundation to identificate the nanoplankton precisely in future.