CHANGES IN COMPETITIVE INTERACTIONS BETWEEN CYANOBACTERIA AND CHLOROPHYTES IN RESPONSE TO RISING CO2 CONCENTRATIONS
Rising atmospheric CO2 concentrations may affect the composition of phytoplankton communities in aquatic systems. Here, we applied a newly developed resource competition model, which links dynamic changes in carbon chemistry, pH and light intensity with competitive interactions between phytoplankton species. To test the model, four ecologically relevant phytoplankton species were selected: three chlorophytes (Monoraphidium griffithii, Scenedesmus obliquus and Chlorella vulgaris) and one bloom-forming cyanobacterium (Microcystis aeruginosa). We grew them individually and pair-wise in chemostats under low (100 ppm) and high (2000 ppm) CO2 levels. The results showed that increasing CO2 levels shift the limiting resource from inorganic carbon to light. Furthermore, the competitive ability of Microcystis increased from a moderate competitor for inorganic carbon to an advanced competitor for light. Our findings suggest that rising CO2 concentrations will have a major impact on the phytoplankton community composition in eutrophic waters, and may promote bloom-forming cyanobacteria.
Verspagen, J., University of Amsterdam, Netherlands, firstname.lastname@example.org
Ji, X., Univeristy of Amsterdam, Netherlands, X.Ji@uva.nl
Stomp, M., University of Amsterdam, Netherlands, email@example.com
Huisman, J., University of Amsterdam, Netherlands, firstname.lastname@example.org
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