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Contrasting effects of rising CO2 on primary production and ecological stoichiometry at different nutrient levels

Authors

  • Jolanda M. H. Verspagen,

    1. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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  • Dedmer B. Van de Waal,

    1. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
    2. Department of Aquatic Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
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  • Jan F. Finke,

    1. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
    Current affiliation:
    1. Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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  • Petra M. Visser,

    1. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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  • Jef Huisman

    Corresponding author
    1. Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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Abstract

Although rising CO2 concentrations are thought to promote the growth and alter the carbon : nutrient stoichiometry of primary producers, several studies have reported conflicting results. To reconcile these contrasting results, we tested the following hypotheses: rising CO2 levels (1) will increase phytoplankton biomass more at high nutrient loads than at low nutrient loads, but (2) will increase their carbon : nutrient stoichiometry more at low than at high nutrient loads. We formulated a mathematical model to predict dynamic changes in phytoplankton population density, elemental stoichiometry and inorganic carbon chemistry in response to rising CO2. The model was tested in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa. The model predictions and experimental results confirmed the hypotheses. Our findings provide a novel theoretical framework to understand and predict effects of rising CO2 concentrations on primary producers and their nutritional quality as food for herbivores under different nutrient conditions.

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