Niche partitioning of picocyanobacterial lineages in the oligotrophic northwestern Pacific Ocean

doi:2015.30.3.223

Algae > Volume 30(3); 2015 > Article

Algae 2015;30(3): 223-232. doi: https://doi.org/10.4490/algae.2015.30.3.223

Dong Han Choi¹^,2, Karen E. Selph³ and Jae Hoon Noh¹^,4^,*

¹Biological Oceanography & Marine Biology Division, Korea Institute of Ocean Science and Technology, Ansan 15627, Korea
²Department of Marine Biotechnology, Korea University of Science and Technology, Daejeon 34113, Korea
³Deparment of Oceanography, University of Hawaii, Honolulu, HI 96822, USA
⁴Department of Marine Biology, Korea University of Science and Technology, Daejeon 34113, Korea

*Corresponding Author

Email: jhnoh@kiost.ac.kr

ABSTRACT

More than 20 and 10 clades / ecotypes of Synechococcus and Prochlorococcus, respectively, have been identified in various oceanic regions. However, their diversity has yet to be thoroughly studied in the northwest Pacific Ocean. Further, spatial distribution of Synechococcus clades in the oligotrophic oceans has been scarcely characterized. To elucidate picocyanobacterial lineage distribution in the northwest Pacific Ocean, 16S-23S internal transcribed spacer sequences of picocyanobacteria were sequenced by barcoded amplicon pyrosequencing method. Additional pyrosequencing library using a primer specific for the Synechococcus subcluster-5.1 was constructed to thoroughly understand Synechococcus diversity in the oligotrophic oceans. In warm pool area, Prochlorococcus was predominant and showed a distinct depthpartitioning between HLII and LL ecotypes. Despite low abundances, diverse Synechococcus clades appeared in the oligotrophic open ocean, showing both vertical and horizontal niche partitioning. Clade II was the predominant Synechococcus clade, especially in upper euphotic depths. In shallow and middle euphotic depths, clades UC-A, III, and CRD1 were distributed broadly. However, a distinct shift in the horizontal distribution was found at ca. 20° N. Conversely, clades XVII and CRD2 dominated at deep euphotic depths and constituted a higher proportion than clade II. These niche-partitioning of Synechococcus clades seemed to be related with temperature, nutrient concentration as well as iron concentration.

Key words: diversity; ecotype; NW Pacific Ocean; Prochlorococcus; pyrosequencing; Synechococcus