Abstract

Most of the biodiversity in oceans is constituted by microbes which dominate the biomass and have key roles in ecosystem functioning and biogeochemical cycling. Recent culture-independent studies of marine planktonic protists have unveiled a large diversity at all phylogenetic scale, notably among the heterotrophic microeukaryotes compartment (2-5 μm cell size), and the existence of novel groups. Among these novel uncultured lineages, Marine Stramenopiles groups (MASTs) are essentially composed of small flagellated eukaryotes (<3 μm) widely distributed in marine systems. These flagellated organisms are recognized to play essential roles for the functioning of marine ecosystems as they channel large amounts of organic carbon to the upper trophic levels and control the population sizes of bacteria and archaea. During the last decade, the microbial diversity and the distribution of the twelve lineages which composed this new stramenopiles are already started, however, little information on their quantitative importance and activity in ecosystems functioning are already acquired. Here, we proposed to i) evaluate the dynamics of the diversity and abundance of these uncultured flagellates in marine environments and ii) investigate their ecological significance in oceans through the study of their grazing activity and the analysis of their general genomic structure. In this proposal, the dynamics, genomics and role of six constitutive lineages of these stramenopiles (MAST-1, -2, -3, -4, -7 and - 8) will be studied by the use of new state-of-art techniques (i.e. 454- and Illumina pyrosequencing, Whole Genome Amplification after flow cytometry cell-sorting) and several standard ones (i.e. grazing experiments, TSA-FISH), applied together on an unique set of environmental samples from a circumglobal navigation providing samples with a wide geographical coverage and from a temporal survey based on a coastal oligotrophic station.

Ramon Massana

Staff scientist

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