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Article

Shift from Carbon Flow through the Microbial Loop to the Viral Shunt in Coastal Antarctic Waters during Austral Summer

1
Royal Netherlands Institute for Sea Research, P.O. Box 59, Den Burg, 1790 AB Texel, The Netherlands
2
Ocean BioGeosciences, National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK
3
Austere Environments Consortium for Enhanced Sepsis Outcomes, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20814, USA
4
British Antarctic Survey, Natural Environmental Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
5
Ecosystems & Environment, Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland
6
Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK
*
Author to whom correspondence should be addressed.
Academic Editor: Johannes F. Imhoff
Microorganisms 2021, 9(2), 460; https://doi.org/10.3390/microorganisms9020460
Received: 28 January 2021 / Revised: 17 February 2021 / Accepted: 18 February 2021 / Published: 23 February 2021
(This article belongs to the Special Issue Polar Microbes)
The relative flow of carbon through the viral shunt and the microbial loop is a pivotal factor controlling the contribution of secondary production to the food web and to rates of nutrient remineralization and respiration. The current study examines the significance of these processes in the coastal waters of the Antarctic during the productive austral summer months. Throughout the study a general trend towards lower bacterioplankton and heterotrophic nanoflagellate (HNF) abundances was observed, whereas virioplankton concentration increased. A corresponding decline of HNF grazing rates and shift towards viral production, indicative of viral infection, was measured. Carbon flow mediated by HNF grazing decreased by more than half from 5.7 µg C L−1 day−1 on average in December and January to 2.4 µg C L−1 day−1 in February. Conversely, carbon flow through the viral shunt increased substantially over the study from on average 0.9 µg C L−1 day−1 in December to 7.6 µg C L−1 day−1 in February. This study shows that functioning of the coastal Antarctic microbial community varied considerably over the productive summer months. In early summer, the system favors transfer of matter and energy to higher trophic levels via the microbial loop, however towards the end of summer carbon flow is redirected towards the viral shunt, causing a switch towards more recycling and therefore increased respiration and regeneration. View Full-Text
Keywords: prokaryotes; Antarctica; viruses; heterotrophic nanoflagellates; microbial loop; viral shunt; carbon; bacteriovory; viral lysis prokaryotes; Antarctica; viruses; heterotrophic nanoflagellates; microbial loop; viral shunt; carbon; bacteriovory; viral lysis
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MDPI and ACS Style

Evans, C.; Brandsma, J.; Meredith, M.P.; Thomas, D.N.; Venables, H.J.; Pond, D.W.; Brussaard, C.P.D. Shift from Carbon Flow through the Microbial Loop to the Viral Shunt in Coastal Antarctic Waters during Austral Summer. Microorganisms 2021, 9, 460. https://doi.org/10.3390/microorganisms9020460

AMA Style

Evans C, Brandsma J, Meredith MP, Thomas DN, Venables HJ, Pond DW, Brussaard CPD. Shift from Carbon Flow through the Microbial Loop to the Viral Shunt in Coastal Antarctic Waters during Austral Summer. Microorganisms. 2021; 9(2):460. https://doi.org/10.3390/microorganisms9020460

Chicago/Turabian Style

Evans, Claire, Joost Brandsma, Michael P. Meredith, David N. Thomas, Hugh J. Venables, David W. Pond, and Corina P.D. Brussaard. 2021. "Shift from Carbon Flow through the Microbial Loop to the Viral Shunt in Coastal Antarctic Waters during Austral Summer" Microorganisms 9, no. 2: 460. https://doi.org/10.3390/microorganisms9020460

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