Protist inhabitants of Polar Regions: microalgae and their phagotrophic predators in extreme terrestrial habitats

Microalgae, whose aquatic fraction is widely explored, also occupy vast terrestrial environments
worldwide. Soil algae are the most important primary producers where vascular plants are absent, as
in the Arctic and Antarctica. They give rise to species-rich microbial food webs in biological soil crusts.
The terrestrial snow- and ice-free areas are in permanent expansion as glaciers retreat, leaving behind
extensive areas of uncovered rock and new soil. Biological soil crusts stabilize the soil surface and have
an important role in soil development. However, the microbial food webs and the nutrient and energy
flow to higher trophic levels remains largely unexplored. We hypothesize that phagotrophic protists,
in particular Cercozoa (Rhizaria) are the most important protistan predators of microalgae in Polar soil
crusts.

We aim to characterize the microbial predator-prey dynamics of polar soils by combining molecular
and traditional culturing techniques. Using high-throughput sequencing of environmental samples, we
will assess the biodiversity and function of soil protists. We will establish co-occurrence networks
between microalgae and their potential predators, which will be validated by food choice experiments
that will allow us to identify each taxon's genuine function in the soil systems.

This project is implemented in the priority program "Antarctic Research with Comparative
Investigations in Arctic Ice Areas", SPP 1158, funded by the German Research Foundation (DFG,
Deutsche Forschungsgemeinschaft).