Abstract

This project addresses the key issue of the relationship between diversity and ecological function in the uncultured heterotrophic eukaryotic microbes dominant in marine planktonic food webs. On one hand, heterotrophic flagellates is a functional group with accepted central roles in marine ecosystems (grazing on picoplankton, nutrient remineralization) and studies so far have treated them as a black box, formed mostly by small and unidentified cells. On the other hand, several recent molecular studies based on environmental rDNA sequences have revealed the existence of unknown eukaryotic microorganisms. A significant number of these sequences were found to be affiliated to the stramenopile taxon, a very heterogeneous assemblage of protists, but were not similar to any known group. Those were named MAST (Marine Stramenopiles), and some of them are heterotrophic and bacterivorous flagellates. Even though scientists start to have an idea of the distribution and phylogenetic relationships within these MAST groups, their role and significance in marine microbial food webs remains largely unknown. In the proposed research project, we will use a combination of innovative methodologies within a multi-disciplinary oceanographic context to open the heterotrophic flagellates black box and investigate the ways MAST organisms interact with the other components of the natural microbial assemblage, particularly with photosynthetic picoplankton, which are major primary producers in the oceans. The host research team is one of the most experienced European teams in that field and the structured training program is designed to provide broad experience in the application of cutting-edge techniques to investigate major cross disciplinary issues in modern microbial ecology and oceanography.

Ramon Massana

Staff scientist

I am microbial ecologists with a deep interest in protist ecology and evolution