MEPS 447:55-75 (2012)  -  DOI: https://doi.org/10.3354/meps09473

ABSTRACT: Data from 7 mesocosms with a gradient in daily nutrient loading rate (L_N) and inverse modelling were used to estimate all C, N and P flows in an idealised food web. The gradient in L_N 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 L_N ≥ natural L_N. 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 L_N (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 L_N. 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. https://doi.org/10.3354/meps09473 Export citation Share:    Facebook - - linkedIn