title: Modeling succession of key resource-harvesting traits of mixotrophic plankton.
abstract: Unicellular eukaryotes make up the base of the ocean food web and exist as a continuum in trophic strategy from pure heterotrophy (phagotrophic zooplankton) to pure photoautotrophy ('phytoplankton'), with a dominance of mixotrophic organisms combining both strategies. Here we formulate a trait-based model for mixotrophy with three key resource-harvesting traits: photosynthesis, phagotrophy and inorganic nutrient uptake, which predicts the trophic strategy of species throughout the seasonal cycle. Assuming that simple carbohydrates from photosynthesis fuel respiration, and feeding primarily provides building blocks for growth, the model reproduces the observed light-dependent ingestion rates and species-specific growth rates with and without prey from the laboratory. The combination of traits yielding the highest growth rate suggests high investments in photosynthesis, and inorganic nutrient uptake in the spring and increased phagotrophy during the summer, reflecting general seasonal succession patterns of temperate waters. Our trait-based model presents a simple and general approach for the inclusion of mixotrophy, succession and evolution in ecosystem models.
authors.affiliation: Department of Biology, VKR Centre for Ocean Life, Marine Biological Section, University of Copenhagen, Helsingør, Denmark.
authors.forename: Terje
authors.initials: T
authors.lastname: Berge
authors.affiliation: National Institute of Aquatic Resources, VKR Centre for Ocean Life, Technical University of Denmark, Charlottenlund, Denmark.
authors.forename: Subhendu
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: Department of Biology, VKR Centre for Ocean Life, Marine Biological Section, University of Copenhagen, Helsingør, Denmark.
authors.forename: Per Juel
authors.identifier: 0000-0003-0228-9621
authors.initials: PJ
authors.lastname: Hansen
authors.affiliation: National Institute of Aquatic Resources, VKR Centre for Ocean Life, Technical University of Denmark, Charlottenlund, Denmark.
authors.forename: Ken H
authors.initials: KH
authors.lastname: Andersen
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D056890:Eukaryota / Q000254:growth & development / Q000378:metabolism; D020387:Food Chain; D052836:Heterotrophic Processes; D008954:Models, Biological; D010788:Photosynthesis; D010839:Phytoplankton / Q000254:growth & development / Q000378:metabolism*; D012621:Seasons; D015048:Zooplankton / Q000254:growth & development / Q000378:metabolism*