École Nationale Supérieure de
Techniques Avancées

Résumé

This report describes the work I have been doing during my internship. In this project I focus on mixotrophy, a mixotrophic plankton is a cell that is able to both achieve photosynthesis and predation on other species. I study here how they are able to compete with specialist species (phytoplankton and zooplankton) despite not being, by definition, completely fitted for the exploitation of a single resource. I will take on this problem with a modeling approach, using a 0D model that I developed from an existing framework. This framework has been written by Ben Mayersohn for his PhD but needed important modifications in order to be applied to this problem. We find that under non-saturated conditions with both feeding sources available in equivalent quantities, mixotrophs are able to become an important component of the modeled ecosystem. They are even able to dominate in some cases, however They rarely exclude specialists from the system. We also find that the coexistence and relative abundance of species is highly dependent on the choices of predation modeling.