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Marine Ecology Progress Series

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MEPS 384:1-12 (2009)  -  DOI:

Optimal uptake kinetics: physiological acclimation explains the pattern of nitrate uptake by phytoplankton in the ocean

S. Lan Smith1,*, Yasuhiro Yamanaka1,2,3, Markus Pahlow4, Andreas Oschlies4

1Ecosystem Change Research Program, Frontier Research Center for Global Change, JAMSTEC, 3173–25 Showa-machi, Kanazawa-ku, Yokohama 236–0001, Japan
2Hokkaido University, Sapporo, Japan
3Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Tokyo 102–0075
4Leibniz Institute of Marine Sciences at Kiel University (IFM–GEOMAR), Kiel, Germany

ABSTRACT: Phytoplankton supply the base of the marine food web and drive the biogeochemical cycles of carbon and nutrients. Over much of the ocean, their growth is limited by their uptake of nitrogen (as nitrate), which has most commonly been described by the hyperbolic Michaelis–Menten (MM) equation. However, the lack of a theory to explain variations in MM constants has hindered our ability to predict the response of marine ecosystems to changes in environmental conditions. The MM equation fits data from short-term experiments well, but does not agree with steady-state experiments over wide ranges of nutrient concentrations. In contrast, the recently developed optimal uptake kinetics (OU) does agree with the latter and can also describe the observed pattern of MM half-saturation constants from field experiments. OU kinetics explains the observed pattern of N uptake as the result of a general physiological trade-off between nutrient uptake capacity and affinity. The existence of a general trade-off would imply a relatively high degree of predictability in the response of nutrient uptake to changing nutrient concentrations and thus provide a basis for predicting effects of climate change on marine ecosystems and biogeochemical cycles.

KEY WORDS: Nutrient uptake · Kinetics · Phytoplankton · Nitrogen · Nitrate · Biogeochemical model

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Cite this article as: Smith SL, Yamanaka Y, Pahlow M, Oschlies A (2009) Optimal uptake kinetics: physiological acclimation explains the pattern of nitrate uptake by phytoplankton in the ocean. Mar Ecol Prog Ser 384:1-12.

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