AME 60:85-95 (2010)  -  DOI: https://doi.org/10.3354/ame01404

Seasonal dynamics of dissolved organic matter and microbial activity in the coastal North Sea

Eva Sintes1,2,*, Karen Stoderegger1, Veronica Parada1, Gerhard J. Herndl1,2

1Department of Biological Oceanography, Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB, Den Burg, The Netherlands
2Department of Marine Biology, Faculty Center of Ecology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria

ABSTRACT: The dynamics of dissolved organic matter (DOM) and microbial activity were monitored in the coastal North Sea over an annual cycle. DOM accumulated during the spring bloom towards the summer, associated with high phytoplankton extracellular release. Accumulation of dissolved organic carbon (DOC) occurred from April to June. During this period, based on the bacterial carbon demand (BCD) of the free-living bacteria and the photosynthetic extracellular release (PER), 85 µM C were derived from sources other than direct DOC release by phytoplankton. Thereafter, from the end of August until December, the DOM concentrations decreased by about half. During this period, at least 269 µM C was removed from the system via the utilization by the bacterial community and/or sedimentation and export. Overall, our data indicate a pronounced seasonal shift in DOM sources supporting BCD. From spring to summer, BCD is almost fully supported by PER alone while in fall and winter, BCD is supported about equally by PER and by the DOM accumulated in the spring–summer period and originating presumably from a variety of DOM production mechanisms.


KEY WORDS: Bacterial activity · Dissolved organic matter · Production · Consumption · North Sea


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Cite this article as: Sintes E, Stoderegger K, Parada V, Herndl GJ (2010) Seasonal dynamics of dissolved organic matter and microbial activity in the coastal North Sea. Aquat Microb Ecol 60:85-95. https://doi.org/10.3354/ame01404

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