Microbial composition and photosynthesis in Antarctic snow algae communities: Integrating metabarcoding and pulse amplitude modulation fluorometry

Abstract

Antarctic snow microbial communities are complex biomes formed by different groups of microorganisms that include algae, bacteria, fungi, and archaea. During spring-summer season, abundant microalgae generate red, orange, pink, green and even yellow patches of snow. The presence of microalgae in snow ecosystems is pivotal for carbon fixation and has the potential to decrease snow albedo. Up to now, the relationship between microorganism diversity and functionality in these ecosystems in Maritime Antarctica is not well understood. In the present study, the microbial composition of different types of colored snow was determined by metabarcoding at Fildes Peninsula, King George Island (Maritime Antarctica). Additionally, light use characteristics were assessed to gain insights into the photosynthetic functionality of different algal groups causing snow blooms. Results from this study indicated that green algae of the Trebouxiophyceae and Chlorophyceae classes dominated the eukaryotes. A high abundance of Stramenopiles was also detected. Besides these findings, Principal Component Analysis was employed, revealing taxonomic distance among sampling sites. Bacteroidetes and Proteobacteria were found to be the most abundant groups in the bacterial communities with an absence of taxonomic distance among sampling sites. However, the presence of Flavobacteria and γ-Proteobacteria varied among samples. Photosynthetic parameters determined for dominating algae within the blooms were dependent on the sites and snow colors. All in all, these results show that snow algae blooms at Fildes Peninsula represent a mixture of algal species with different light requirements.