MIXO-DOM: Linking alternative nutritional strategies in phytoplankton to dissolved organic matter pools

Mixotrophic protists are single celled organisms that combine autotrophic and heterotrophic behaviors to meet their energy and growth needs. Depending on the type of trophic behavior, mixotrophs can live fully as autotrophs, fully as heterotrophs, or require both metabolic pathways and utilize a combination of autotrophy and feeding on dissolved to particulate forms of organic matter. Mixotrophy has been studied through the lenses of ecosystem trophic state, but not much is known about freshwater mixotrophs and their relationship to organic matter availability and composition. Likewise, there is considerable research around the balance between respiration and primary production under different organic matter conditions in aquatic ecosystems, but a similar focus is lacking for mixotrophy.  It is possible that habitat conditions that promote complex and reactive dissolved organic matter pools might also promote mixotrophic behavior. This could be through direct consumption of dissolved organic matter or indirectly by promoting heterotrophic bacterial growth, which are then consumed by mixotrophs. Mixotrophy might also be a mechanism to alleviate nutrient limitation by accessing bound nutrients.  Similar, ecosystems with dark water might promote mixotrophy as a means to alleviate light (energy) limitations on autotrophy. MIXO-DOM will explore the following research questions: Are the presence and activity of mixotrophic protists linked to pools of organic matter?