Into the dark: diversity and ecology of fungi and protists in the twilight zone of polar freshwaters environments

Polar freshwater environments represent oasis of life and hotspot of biodiversity in arid polar desert and in these freshwater habitats, cold temperature can be accompanied by freeze-thawing cycling, darkness and large variations in nutrients and salinity, and therefore the biology of these ecosystems is dominated by microbial life with plants, insects and animals being mostly absent. Microbial communities from diverse communities in the water column and biofilms along the bottom of freshwater environments.

The water column of lakes and meltwater ponds can be highly stratified with illuminated oxygen containing water at the surface but dark and anoxic layers at the bottom.

Recent molecular analyses have shown that fungi and protists including ciliates, amoeba and flagellates are abundant and can even be detected in the more extreme deeper water layers that lack of oxygen, but their taxonomic richness, diversity and biogeography remain poorly characterised. The few existing relevant studies indicate that there is significant genomic and functional novelty in these systems that demand further study in order to understand key ecological processes driven by microbes in polar regions.

Anaerobic protists have specialist mitochondria for their energy metabolism in the absence of oxygen and they have been shown to be major predator of bacteria in aquatic environments. However, polar environments have received little attention, and their ecological function in food webs and interactions with bacterial assemblages are not known yet.

The aims of the project are therefore to perform a comprehensive environmental DNA diversity assessment of fungi and protists in low oxygen and anoxic waters in lakes and meltwater ponds across the Arctic and Antarctic, and characterise phylogenetic and biogeography relationships, and evaluate the relative importance of nutritional roles (heterotrophs: grazers, predators, parasites, symbioses) in the Polar regions.

Genomic adaptations of key microbial players to polar environments could be studied using cutting edge high throughput sequencing and bioinformatics. The research outcomes will also be relevant for the evolution of eukaryotes on Early Earth.

The project will use a multi-faceted approach and provide the PhD student with training in molecular, microbiology techniques and bioinformatics, in particular environmental DNA and RNA, high throughput sequencing, microbial community structure analysis, genomics, metagenomics and phylogenetic interference.