Systematics, Biodiversity and Evolution of Plants

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Monday January 08, 2024, 5 pm, CET, GMT +1


Per Juel Hansen*

Acquired phototrophy in marine protists 

* Marine Biological Section, University of Copenhagen


Most marine biology text books still split marine planktonic protists into “animals” that feed, and “plants” that photosynthesize and take up inorganic nutrients. This is also how protists usually are dealt with in food web models. However, many protists are mixoplanktonic, i.e. they photosynthesize and engulf prey organisms. In this presentation, I will focus on mixotrophy in protists that lack chloroplasts of their own and thus are dependent on acquired phototrophy. Protists with acquired phototrophy are ubiquitous and can be found in eutrophic coastal waters as well as in oligotrophic oceanic waters. In some cases, they even form blooms or produce phycotoxins that accumulate in the marine food web. The group comprises of protists with endo- and ecto-symbionts as well as protists that sequester chloroplasts, and sometimes, other cell organelles from their prey. It is functionally a quite diverse group, which covers almost the entire mixotrophic spectrum from predominantly phototrophic to predominantly heterotrophic species. In this presentation, I will show examples of their functional biology and ecophysiology, and discuss their success in different habitats.