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The microbial food web during the Arctic winter

AuthorsPedrós-Alió, Carlos ; Alonso-Sáez, Laura ; Fernández-Gómez, Beatriz ; Sala, M. Montserrat ; Vaqué, Dolors ; Rodríguez-Martínez, Raquel ; Massana, Ramon ; Bertilsson, S.; Galand, Pierre E. ; Casamayor, Emilio O.
Issue Date24-Apr-2012
CitationISME14 - Abstracts Contributed Session (2012)
AbstractThe microbial ecology of polar oceans is still poorly known, especially in winter, when only a handful of studies have been carried out. The Canadian IPY project Circumpolar Flaw Lead Polynya Study included a time series from the darkest (December 2007) to the most lit times of the year (June 2008) in Amundsen Gulf, a dynamic area due to the presence of a polynya. Our objective was to determine the activities and trophic relationships of planktonic microorganisms during winter. Chlorophyll a decreased during the fall and early winter as expected. In middle February, however, chlorophyll started to increase exponentially despite the low light levels. This could be attributed to small flagellates, particularly Micromonas. We determined grazing rates on these algae that were of the same order of magnitude as the in situ net decrease rates in January. This grazing was mostly due to relatively large nanoflagellates (non bacterivorous). Heterotrophic bacteria increased in numbers about a month later than the algal bloom and bacterivory by small pico and nanoflagellates followed. Thus, the first trophic chain to become active after the total darkness period was autotrophic picoflagellates (mostly Micromonas) to large nanoflagellates. We studied the trophic mode of the heterotrophic bacteria and archaea with custom designed BIOLOG plates. We also carried out enrichment experiments in the dark and followed the development of different prokaryotes determining their ability to use leucine and bicarbonate by microautoradiography combined with FISH (fluorescence in situ hybridization). Finally, we determined bacterivory rates. The bacteria were active on the substrates assayed. The archaea, however, showed very low activities both with organic substrates and with bicarbonate. Their main source of carbon, therefore, remains elusive
DescriptionIPY2012 Conference Montréal. From Knowledge to Action, 22-27 April 2012, Montréal, Canada
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Appears in Collections:(CEAB) Comunicaciones congresos
(ICM) Comunicaciones congresos
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