MEPS 447:55-75 (2012)  -  doi:10.3354/meps09473

Carbon, nitrogen and phosphorus resource supply and utilisation for coastal planktonic heterotrophic bacteria in a gradient of nutrient loading

Olav Vadstein1,*, Tom Andersen2, Helge R. Reinertsen3, Yngvar Olsen3

1Department of Biotechnology, and 3Department of Biology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
2University of Oslo, Department of Biology, PO Box 1066 Blindern, 0316 Oslo, Norway

ABSTRACT: Data from 7 mesocosms with a gradient in daily nutrient loading rate (LN) and inverse modelling were used to estimate all C, N and P flows in an idealised food web. The gradient in LN created autotrophic production (AP) of 7 to 314 µg C l−1 d−1 (mean values over 18 d). The production of dissolved organic C (DOC) decreased from 240 to 40% of AP, and was dominated by heterotrophs (80 to 58%), with heterotrophic bacteria (BAC) producing 48 ± 8% (means ± SD) by excretion or lysis. The consumption of DOC by BAC was 133 to 86% of AP, and DOC accumulated when experimental LN ≥ natural LN. C of BAC origin constituted 5.5 to 0.2% of the C consumed by copepods. The production of dissolved N and P was mainly by heterotrophs (92 ± 2% of DN, 92 ± 4% DP), but autotrophs produced 26 ± 7% of dissolved organic N (DON) and 21 ± 8% of dissolved organic P (DOP). For the production of inorganic N and P (DIN and DIP, respectively), BAC predators ­produced >50% of DIN and >70% of DIP at low or moderate LN (averages 37 ± 16% of DIN and 66 ± 14% of DIP). The contribution by BAC was low for DIN (12 ± 6%) and zero for DIP. For the re-mineralisation of N and P, the significance of BAC was as N and P rich food particles. DOP accumulated more than DOC, despite the high demand for P. Turnover time of dissolved organic matter (DOM) decreased from around 80 to 12 d with increasing LN. These data provide new insights into the role of various functional groups of organisms for the cycling of DOM, and to the differences in C, N and P cycling.


KEY WORDS: DOM production · DOM utilisation · Heterotrophic bacteria · ­Community ­interactions · DOC accumulation · Re-mineralisation · Inverse modelling ∙


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Cite this article as: Vadstein O, Andersen T, Reinertsen HR, Olsen Y (2012) Carbon, nitrogen and phosphorus resource supply and utilisation for coastal planktonic heterotrophic bacteria in a gradient of nutrient loading. Mar Ecol Prog Ser 447:55-75

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