Diversity and assembly processes of microbial eukaryotic communities in Fildes Peninsula Lakes (West Antarctica)

Abstract

Abstract. 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.

Seasonal shifts in microbial diversity in the lakes of Fildes Peninsula, King George Island, Maritime Antarctica

“…Nevertheless, a recent study performed in Fildes Peninsula during the ice-free period found Chrysophyta to be dominant, while Chlorophyta were the second most abundant group (Zhang et al 2022). Zhang et al (2022) is the first study in the region using NGS for phytoplankton analysis, and differences in the methods employed could be a key factor explaining the differences in the results. We recognize that the chemotaxonomic approach we employed by analysing pigments does not enable high-resolution determinations of phytoplankton taxa.…”

“…Chlorophytes have also been shown to dominate in Antarctic lakes but usually under relatively high nutrient concentrations, such as those found in summer when lakes are ice free (Izaguirre et al 1998, Rochera et al 2013. Nevertheless, a recent study performed in Fildes Peninsula during the ice-free period found Chrysophyta to be dominant, while Chlorophyta were the second most abundant group (Zhang et al 2022). Zhang et al (2022) is the first study in the region using NGS for phytoplankton analysis, and differences in the methods employed could be a key factor explaining the differences in the results.…”

“…2019) and Potter and Fildes peninsulas on King George Island (Vinocur & Unrein 2000, Schiaffino et al . 2009, Zhang et al 2022), where authors have studied phytoplankton, zooplankton and bacterioplankton dynamics. Rochera et al (2017) recorded major changes in plankton communities on Byers Peninsula (Livingston Island) during the transition to the ice-free period when light availability and allochthonous nutrient fluxes were high.…”

“…Much of our understanding of annual cycles in Maritime Antarctic lakes was developed from studies on Signy Island (South Orkney Islands), which showed marked seasonal and interannual variations in planktonic population dynamics (Quayle et al 2003). Limnological research is often focused near research stations, with well-studied lake clusters present near Hope Bay and Cierva Point on the AP (Izaguirre 2003, Schiaffino et al 2009, Allende & Mataloni 2013, Byers Peninsula on Livingston Island (Toro et al 2007), James Ross Island (Roman et al 2019) and Potter and Fildes peninsulas on King George Island (Vinocur & Unrein 2000, Schiaffino et al 2009, Zhang et al 2022, where authors have studied phytoplankton, zooplankton and bacterioplankton dynamics. Rochera et al (2017) recorded major changes in plankton communities on Byers Peninsula (Livingston Island) during the transition to the ice-free period when light availability and allochthonous nutrient fluxes were high.…”

“…Montecino et al 1991) or surveys of basic limnological parameters (e.g. Préndez & Carrasco 2003, Shevnina & Kourzeneva 2017, although one recent study applied NGS to the analysis of microeukaryote communities in five Fildes Peninsula lakes (Zhang et al 2022). Finally, the only study of bacterioplankton diversity examined three ponds and one lake from Fildes Peninsula during five consecutive summers, employing a bacterial culture-dependent approach (Morel et al 2015).…”