Allochthonous Carbon - a major driver of bacterioplankton production in the subarctic Northern Baltic Sea

Heterotrophic bacteria are, in many aquatic systems, reliant on autochthonous organic carbon as their energy source. One exception is low-productive humic lakes, where allochthonous dissolved organic matter (ADOM) is the major driver. We hypothesized that bacterial production (BP) is similarly regul...

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Bibliographic Details
Published in:Microbial Ecology
Main Authors: Figueroa, Daniela, Rowe, Owen, Paczkowska, Joanna, Legrand, Catherine, Andersson, Agneta
Format: Article in Journal/Newspaper
Language:English
Published: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap 2016
Subjects:
Allochthonous organic matter
carbon utilization
bacterioplankton production
Sub-arctic estuary
Baltic Sea
Ecology
Ekologi
Arctic
Spring River
Northern Sweden
Subarctic
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-117966
https://doi.org/10.1007/s00248-015-0714-4
Description
Summary:Heterotrophic bacteria are, in many aquatic systems, reliant on autochthonous organic carbon as their energy source. One exception is low-productive humic lakes, where allochthonous dissolved organic matter (ADOM) is the major driver. We hypothesized that bacterial production (BP) is similarly regulated in subarctic estuaries that receive large amounts of riverine material. BP and potential explanatory factors were measured during May–August 2011 in the subarctic Råne Estuary, northern Sweden. The highest BP was observed in spring, concomitant with the spring river-flush and the lowest rates occurred during summer when primary production (PP) peaked. PLS correlations showed that ∼60 % of the BP variation was explained by different ADOM components, measured as humic substances, dissolved organic carbon (DOC) and coloured dissolved organic matter (CDOM). On average, BP was threefold higher than PP. The bioavailability of allochthonous dissolved organic carbon (ADOC) exhibited large spatial and temporal variation; however, the average value was low, ∼2 %. Bioassay analysis showed that BP in the near-shore area was potentially carbon limited early in the season, while BP at seaward stations was more commonly limited by nitrogen-phosphorus. Nevertheless, the bioassay indicated that ADOC could contribute significantly to the in situ BP, ∼60 %. We conclude that ADOM is a regulator of BP in the studied estuary. Thus, projected climate-induced increases in river discharge suggest that BP will increase in subarctic coastal areas during the coming century.

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