Paramecium - Deutsche Gesellschaft für Protozoologie / German ...

In situ diversity of marine heterotrophic flagellates
Ramon Massana
Institut de Ciències del Mar, CSIC. Barcelona, Spain
Heterotrophic flagellates are ubiquitous protists that play key roles in
planktonic marine food webs. They are the main consumers of prokaryotes
and participate directly in nutrient remineralization. Both
direct measurements and size-fractionation grazing experiments have
revealed that these assemblages are numerically dominated by very
small cells of 2-3 µm in diameter, which mostly remain unidentified.
Recent molecular surveys of marine picoeukaryotes have revealed a
huge diversity and the presence of novel lineages. Here I will show
that some of these novel lineages, in particular some organisms forming
novel clades within the stramenopile radiation (MAST, Marine
Stramenopiles), account for a significant part of heterotrophic flagellates
assemblages. Phylogenetic probes against different MAST
groups have been designed and optimized for FISH to follow the
abundance and distribution in the environment of the corresponding
organisms. These probes can be further applied in experiments to
infer the growth and grazing rates of these still uncultured flagellates.
Tools to open the black box of marine heterotrophic flagellates,
which are composed of diverse groups with diverse functions, start to
be available.
ramonm@icm.csic.es
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