Biogeography of Arctic picoeukaryotes during summer of 2012

Sampling

Information on recent photosynthetic biomass distribution and biogeography of Arctic marine pico-eukaryotes (0.2 3 m) are needed to better understand consequences of environmental change for Arctic marine ecosystems. We analysed pico-eukaryote biomass and community composition in Fram Strait and larger parts of the central Arctic Ocean (Nansen Basin, Amundsen Basin) by chlorophyll a (Chl a) measurements, Automated Ribosomal Intergenic Spacer Analysis (ARISA), and 454-pyrosequencing. Samples were collected during summer 2012, the year with the latest record sea ice minimum. Chl a values were highest in eastern Fram Strait and pico-plankton accounted for 60-90% of Chl a biomass during the observation period. ARISA-patterns and 454-pyrosequencing revealed, that pico-eukaryote distribution is closely related to water mass distribution in the euphotic zone of the Arctic Ocean. Phaeocystaceae, Micromonas sp., Dinophyceae and Syndinales constitute a high proportion of sequence reads, while sequence abundance of autotrophic Phaeocystaceae and mixotrophic Micromonas sp. was inversely correlated. Highest sequence abundances of Phaeocystaceae were observed in the warm Atlantic waters in Fram Strait, while Micromonas sp. dominated the abundant biosphere in the arctic halocline. Our results are from particular interest, because there are hypotheses that environmental conditions in Nansen Basin might become more similar to the current conditions in Fram Strait. In regard to this we propose that in response biodiversity and biomass of pico-eukaryotes in Nansen Basin could resemble those currently observed in the Fram Strait in the future. This would significantly alter biogeochemical cycles in that area, that constitutes a large part of the central Arctic Ocean.

Method steps

1. Pipeline used: https://www.ebi.ac.uk/metagenomics/pipelines/5.0