Diversity and Assembly Processes of Microbial Eukaryotic Communities in Fildes Peninsula Lakes (west Antarctica)

The diversity, co-occurrence patterns, and assembly processes of microbial eukaryotes (0.2–20 µm) in Antarctic freshwater lakes are not well understood, despite their wide distribution and ecological importance. This study used Illumina high-throughput sequencing to investigate the microbial eukaryotic communities of five freshwater lakes on the Fildes Peninsula over three summer seasons. A total of 28 phyla were detected, with phytoplankton occupying the highest percentage of sequences (accounting for up to 98 %). The dominant taxa consisted of Chrysophyta, Chlorophyta, and Cryptophyta. The species richness (113–268) and Shannon index (1.70–3.50) varied among the lakes, with higher values recorded in Lake Chang Hu and Lake Kitec and the lowest value obtained for Lake Yue Ya. There were significant differences between the microbial eukaryotic communities of the lakes, with spatial and temporal heterogeneity in the relative abundance of the dominant taxa (P<0.05). Environmental variables explained about 39 % of the variation in community structures, with water temperature and phosphate identified as the driving factors (P<0.05). Network analysis revealed comprehensive co-occurrence relationships (positive correlation 82 % vs. negative correlation 18 %). The neutral community model revealed that neutral processes explained more than 55 % of the community variation. Stochastic processes (e.g. homogenizing dispersal and undominated processes) predominated in community assembly over the deterministic processes. These findings demonstrate the diversity of the microbial eukaryotic communities in the freshwater lakes of the Fildes Peninsula and have important implications for understanding the community assembly in these ecosystems.