Hisashi Endo

Diatoms and haptophytes are two major phytoplankton groups, playing pivotal roles in global biogeochemical cycles and marine ecosystems. In general, diatoms have higher growth rates than haptophytes, whereas haptophytes tend to have higher nutrient uptake affinity. However, precise linkages between their ecological traits and geographical distributions remain poorly understood. Herein, we examined the basin-scale variability of the abundance and taxonomic composition of these two phytoplankton g

Abstract. Iron (Fe) can limit phytoplankton productivity in approximately 40% of the global ocean, including in high-nutrient, low-chlorophyll (HNLC) waters. However, there is little information available on the impact of CO2-induced seawater acidification on natural phytoplankton assemblages in HNLC regions. We therefore conducted an on-deck experiment manipulating CO2 and Fe using Fe-deficient Bering Sea water during the summer of 2009. The concentrations of CO2 in the incubation bottles were

Haptophytes are important members of the marine microbial community with high diversities in taxonomy and ecological function. However, little is known about the distribution and diversity of this algal group in and around the Kuroshio. Here, we present a fine-scale community structure and diversity of haptophytes in the surface and deep chlorophyll maximum (DCM) layers across the Kuroshio in the Tokara Strait. Phytoplankton pigment analysis revealed that the haptophytes were the most dominant p

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 ex

Haptophytes are one of the most ecologically successful phytoplankton groups in the modern ocean and tend to maintain balanced and stable communities across various environments. However, little is known about the mechanisms that enable community stability and ecological success. To reveal the community characteristics and interactions among haptophytes, we conducted comprehensive observations from the upstream to downstream regions of the Kuroshio Current. Haptophyte abundance and taxonomy were

Microeukaryotes are critical components of sinking particles contributing to carbon export from the surface to deep oceans. However, the knowledge of the sinking microeukaryotic communities and their dynamics is currently limited. In this study, we applied 18S rRNA gene metabarcoding to investigate the microeukaryotic communities in sinking and suspended particles distinguished by marine snow catchers during spring in the Oyashio region. Sinking particles displayed distinct communities and lower

Abstract Viruses are important regulatory factors of the marine microbial community including microeukaryotes. However, little is known about their role in the northern Chukchi Sea in the Arctic basin, which has oligotrophic conditions in summer. To clarify the link between microbial eukaryotic communities and viruses as well as environmental conditions, we investigated the community structures of microeukaryotes (from 3 to144 μ m and from 0.23 μ m size bio‐particles collected from seawater) and