Molecular diversity and temporal variation of picoeukaryotes in two Arctic fjords,Svalbard |
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Authors: | Email author" target="_blank">N?S?rensenEmail author N?Daugbjerg T?M?Gabrielsen |
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Institution: | 1.Marine Biological Section, Department of Biology,University of Copenhagen,Copenhagen K,Denmark;2.The University Centre in Svalbard,Longyearbyen,Norway |
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Abstract: | Picoeukaryotes (protists <3 μm) form an important component of Arctic marine ecosystems, although knowledge of their diversity
and ecosystem functioning is limited. In this study, the molecular diversity and autotrophic biomass contribution of picoeukaryotes
from January to June 2009 in two Arctic fjords at Svalbard were examined using 18S environmental cloning and size-fractioned
chlorophyll a measurements. A total of 62 putative picoeukaryotic phylotypes were recovered from 337 positive clones. Putative picoeukaryotic
autotrophs were mostly limited to one species: Micromonas pusilla, while the putative heterotrophic picoeukaryote assemblage was more diverse and dominated by uncultured marine stramenopiles
(MAST) and marine alveolate groups. One MAST-1A phylotype was the only phylotype to be found in all clone libraries. The diversity
of picoeukaryotes in general showed an inverse relationship with total autotrophic biomass, suggesting that the conditions
dominating during the peak of the spring bloom may have a negative impact on picoeukaryote diversity. Picoplankton could contribute
more than half of total autotrophic biomass before and after the spring bloom and benefited from an early onset of the growth
season, whereas larger cells dominated the bloom itself. |
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