engleski

Picoeukaryotic plankton composition revealed by high-throughput sequencing: first data for the Adriatic Sea

The diversity of marine picoeukaryotes (cells <3 µm) in plankton of the Adriatic Sea has received limited attention. Importance of marine picoeukaryotes lies not only in primary production, but in roles as decomposers or predators that regulate prokaryotic populations. This study investigates picoeukaryotic community throughout water column from the surface to aphotic layers from coastal to open sea. Sampling was conducted within BIOTA (Bio-tracing Adriatic Water Masses) cruise in the South Adriatic Sea in March 2016. Size-fractioned samples (0, 2-3 µm) in high volumes (approx. 8 L) were collected at various depths in respect to bio-optical and physico-chemical parameters. High-throughput sequencing of 18S rRNA V4 amplicons revealed absolute dominance of heterotrophic picoeukaryotes at all stations and depths while photosynthetic picoeukaryotes had relative abundance under 5%. General higher respiration than photosynthesis process in spring of 2016 was confirmed with optical measurements. Picoeukaryotes were mostly represented by parasitic Dinophyceae, Syndiniales group. Photosynthetic picoeukaryotes were represented with class Mamiellophyceae, which had higher relative abundance in open waters. Interesting shifting pattern in picoeukaryotic community was observed at open sea station P1000, depth 80 m where radiolarians from order Collodaria, family Sphaerozoidae appeared in high relative abundance (23%) which was particularly interesting with regard to ongoing climate changes and impact on the Adriatic Sea.

picoukaryotes, high-throughput sequencing, Adriatic Sea, Syndiniales, Collodaria

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