Diversity and Ecology of Fungal Assemblages Present in Lakes of Antarctica

The biota of Antarctica lakes is constituted by simplified aquatic food webs characterised by low zooplankton biomass, absence of fish, and low floristic diversity (algae and aquatic mosses), but primarily encompassing microorganisms such as viruses, cyanobacteria, bacteria, archaea, and fungi. Among the microbial communities, fungi are widely spread in the different Antarctic lakes and, despite the extreme conditions of the region, show moderate diversity and richness with dominance of a few taxa. Endemic fungal species are found in the Antarctic lakes; however, the majority of fungi are characterised as cosmopolitan cold-adapted species that arrive as propagules from outside Antarctica and are adapted to disperse in the temporary or perennial water bodies, including saline and freshwater lakes. These fungi are subjected to freezing and melting cycles, low temperatures, and high incidence of UV radiation, mainly during the long periods of light in Austral summers. In contrast, in Austral winters, fungi are exposed to extreme freezing conditions. Additionally, in the lakes of Antarctica, fungi act as decomposers and interact with other organisms, such as parasites, or are in symbiotic associations, which consequently influence the lake food web dynamics. In Antarctica, cold-adapted cosmopolitan and psychrophilic fungi have the ability to grow, colonise substrates, and produce extracellular cold-active enzymes and other metabolites, which actively participate in the cycling of nutrients in lakes. In this chapter, we present the characteristics of different Antarctic lakes and shed light on various aspects of taxonomy, ecology, and potential applications of freshwater fungi from maritime and continental Antarctica.