Abstract

Recent molecular studies based on sequencing rDNA directly retrieved from the marine plankton have revealed the existence of eukaryotic microorganisms never seen before. A significant number of the sequences retrieved affiliated within the stramenopiles, a very heterogeneous group that includes from diatoms to fungi-like cells, but were not similar to any known organism and were then named “novel stramenopiles”. The main objective of the project ESTRAMAR is the phylogenetic and ecological characterization of this novel group. First, we will analyze in detail the phylogenetic relationships among novel stramenopiles and other organisms, since we know this is a very diverse and complex group. Then, we will design phylogenetic probes against the most important subgroups that will allow visualizing the organisms in natural samples by FISH (Fluorescent In Situ Hybridization). Using FISH and the new probes, we will study the abundance and distribution of novel stramenopiles in samples obtained in a coastal seasonal study and in oceanographic cruises of opportunity. Finally, we will perform experiments to assess the ecological role of this novel group. Some novel stramenopiles are small heterotrophic flagellates that consume bacteria. We will develop a method to estimate the ability and rates of bacterivory by each different subgroup of novel stramenopiles. Moreover, we will also assess whether some subgroups are able to incorporate dissolved organic matter. The results expected during the project ESTRAMAR will contribute significantly to understand this novel group of microorganisms and will have clear implications for biodiversity studies and the understanding of the structure and function of marine food webs.

Ramon Massana

Staff scientist

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