Pyrosequencing surveys of phytoplankton diversity and community structure in the East China sea aound Jeju lslnad (Korea) and their implications

Abstract

Jeju Island (Korea) is located at the boundary of temperate and subtropical regions, and surrounded by the northern part of the East China Sea, that is affected by the Kuroshio warm current. Thus, this oceanic area has been considered as a potential monitoring site for ecosystem changes caused by global warming. In the present stuy, we assessed molecular diversity and community structure of phytoplankton in the East China Sea around Jeju Island, using 18S rRNA pyrosequencing. This included 8 water samples that were collected four from the surface, two at 30m, and two at 50m-depths at April 12, 20112. Pyrosequencing results showed 15,498 unique sequences from 15,534 tag amplicons, forming 200 phylotypes (vs. 45 spp. by morphology) from four surface sites. Upon comparisons, we found that phylotypes from surface, 30m-, and 50m-depths from the same sampling site were very similar. Of surface samples, we observed that dinoflagellates (29%), stramenopiles (31%), and chlorophytes (>39%) existed as major taxa, with minor taxa representing cryptophyte, prymnesiophytes, Telonemida etc. In most sites, Karlodinium sp., Skeletonema sp., and Ostreococcus sp. occurred dominantly; however, we found species diversity and community stuctures were quite different from one another. Most detected phylotypes were affiliated to undescribed species in the studied area. This study provides primarily a list of phs a potential monitoring site for ecosystem changes caused by global warming. In the present stuy, we assessed molecular diversity and community structure of phytoplankton in the East China Sea around Jeju Island, using 18S rRNA pyrosequencing. This included 8 water samples that were collected four from the surface, two at 30m, and two at 50m-depths at April 12, 20112. Pyrosequencing results showed 15,498 unique sequences from 15,534 tag amplicons, forming 200 phylotypes (vs. 45 spp. by morphology) from four surface sites. Upon comparisons, we found that phylotypes from surface