title: Response of Spring Diatoms to CO2 Availability in the Western North Pacific as Determined by Next-Generation Sequencing.
abstract: Next-generation sequencing (NGS) technologies have enabled us to determine phytoplankton community compositions at high resolution. However, few studies have adopted this approach to assess the responses of natural phytoplankton communities to environmental change. Here, we report the impact of different CO2 levels on spring diatoms in the Oyashio region of the western North Pacific as estimated by NGS of the diatom-specific rbcL gene (DNA), which encodes the large subunit of RubisCO. We also examined the abundance and composition of rbcL transcripts (cDNA) in diatoms to assess their physiological responses to changing CO2 levels. A short-term (3-day) incubation experiment was carried out on-deck using surface Oyashio waters under different pCO2 levels (180, 350, 750, and 1000 μatm) in May 2011. During the incubation, the transcript abundance of the diatom-specific rbcL gene decreased with an increase in seawater pCO2 levels. These results suggest that CO2 fixation capacity of diatoms decreased rapidly under elevated CO2 levels. In the high CO2 treatments (750 and 1000 μatm), diversity of diatom-specific rbcL gene and its transcripts decreased relative to the control treatment (350 μatm), as well as contributions of Chaetocerataceae, Thalassiosiraceae, and Fragilariaceae to the total population, but the contributions of Bacillariaceae increased. In the low CO2 treatment, contributions of Bacillariaceae also increased together with other eukaryotes. These suggest that changes in CO2 levels can alter the community composition of spring diatoms in the Oyashio region. Overall, the NGS technology provided us a deeper understanding of the response of diatoms to changes in CO2 levels in terms of their community composition, diversity, and photosynthetic physiology.
authors.affiliation: Faculty of Environmental Earth Science/Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.|CREST, Japan Science and Technology, Sapporo, Hokkaido, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Endo
authors.affiliation: Central Research Institute of Electric Power Industry, Abiko, Chiba, Japan.|Research and Development Center for Global Change, Japan Agency for Marine Earth-Science and Technology (JAMSTEC), Yokosuka, Kanagawa, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Sugie
authors.affiliation: Central Research Institute of Electric Power Industry, Abiko, Chiba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoshimura
authors.affiliation: Faculty of Environmental Earth Science/Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan.|CREST, Japan Science and Technology, Sapporo, Hokkaido, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology*; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D017377:Diatoms / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D017753:Ecosystem; D015870:Gene Expression; D056426:Genetic Loci; D016678:Genome; D059014:High-Throughput Nucleotide Sequencing; D010140:Pacific Ocean; D010788:Photosynthesis / Q000187:drug effects; D010802:Phylogeny; D010839:Phytoplankton / Q000145:classification / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics* / Q000378:metabolism; D012623:Seawater
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D002245:Carbon Dioxide; C101625:RbcL protein, plastid; D012273:Ribulose-Bisphosphate Carboxylase