동태평양과 서태평양에서의 picocyanobacteria 다양성 변동

Abstract

In order to elucidate diversity of marine picocyanobacteria within euphotic depth of the north-west Pacific (NWP) and eastern equatorial Pacific (EEP), high-throughput pyrosequencing of 16S-23S rRNA internal transcribed spacer sequences were conducted in fifteen and six stations, respectively. Sampling stations of NWP and EEP were located in oligotrophic warm pool area and high nutrient low chlorophyll (HNLC) area, respectively. In NWP, Prochlorococcus sequences dominated in most samples except 3 samples, showing uniform distribution of picocyanobacterial diversity in NWP. On the contrary, latitudinal change in picocyanobacterial diversity was remarkable in EEP. At upper euphotic depths of stations N5 and N7, Synechococcus CRD1 clade occupied 72~98% of picocyanobacterial sequences, whereas at stations N13 and N15, Prochlorococcus HLII clade was most dominant. Further, Synechococcus clade VII was most dominant in boundaries of the CRD1 and HLII dominant waters. This dynamic change of picocyanobacterial diversity in EEP seems to be related with vertical and meridional circulation in equatorial latitudes. In lower euphotic zone below 100 m depth, low light-adapted Prochlorococcus was found to be dominant in both areas. However, LLI and LLIV ecotypes, respectively, occupied more fractions in NWP and EEP. These results suggest picocyanobacterial lineages distribution could be changed dynamically, probably due to physicoche conducted in fifteen and six stations, respectively. Sampling stations of NWP and EEP were located in oligotrophic warm pool area and high nutrient low chlorophyll (HNLC) area, respectively. In NWP, Prochlorococcus sequences dominated in most samples except 3 samples, showing uniform distribution of picocyanobacterial diversity in NWP. On the contrary, latitudinal change in picocyanobacterial diversity was remarkable in EEP. At upper euphotic depths of stations N5 and N7, Synechococcus CRD1 clade occupied 72~98% of picocyanobacterial sequences, whereas at stations N13 and N15, Prochlorococcus HLII clade was most dominant. Further, Synechococcus clade VII was most dominant in boundaries of the CRD1 and HLII dominant waters. This dynamic change of picocyanobacterial diversity in EEP seems to be related with vertical and meridional circulation in equatorial latitudes. In lower euphotic zone below 100 m depth, low light-adapted Prochlorococcus was found to be dominant in both areas. However, LLI and LLIV ecotypes, respectively, occupied more fractions in NWP and EEP. These results suggest picocyanobacterial lineages distribution could be changed dynamically, probably due to physicoch