Community Assembly and Co-Occurrence Patterns of Microeukaryotes in Thermokarst Lakes of the Yellow River Source Area

Ze Ren,Xuan Jia,Kang Ma,Cheng Zhang,Qing Wang,Xia Li

doi:10.3390/microorganisms10020481

Abstract

Thermokarst lakes are important aquatic ecosystems in cold regions, experiencing several changes due to global warming. However, the fundamental assembly mechanisms of microeukaryotic communities in thermokarst lakes are unknown. In this study, we examined the assembly processes and co-occurrence networks of microeukaryotic communities in sediment and water of thermokarst lakes in the Yellow River Source Area. Sediment microeukaryotic communities had a significantly lower α-diversity but higher β-diversity than water microeukaryotic communities. pH, sediment organic carbon, and total phosphorus significantly affected taxonomic and phylogenetic diversity of sediment communities, while conductivity was a significant driver for water communities. Both sediment and water microeukaryotic communities were strongly governed by dispersal limitation. However, deterministic processes, especially homogenous selection, were more relevant in structuring microeukaryotic communities in water than those in sediment. Changes in total nitrogen and phosphorus in sediment could contribute to shift its microeukaryotic communities from homogeneous selection to stochastic processes. Co-occurrence networks showed that water microeukaryotic communities are more complex and interconnected but have lower modularity than sediment microeukaryotic communities. The water microeukaryotic network had more modules than the sediment microeukaryotic network. These modules were dominated by different taxonomic groups and associated to different environmental variables.

Highlights

Introduction published maps and institutional affilThermokarst lakes are shallow thaw lakes formed after the thawing of ice-rich permafrost and widely distributed in cold regions with high altitude or latitude [1,2]
We investigated microeukaryotes in 23 thermokarst lakes in the Yellow River Source Area (YRSA) on the Qinghai–Tibet Plateau (QTP) using 18S rRNA gene sequencing
Results of this study suggest that both sediment and water microeukaryotic communities are strongly governed by stochastic assembly processes, especially dispersal limitation (Figure 3)

Summary

Introduction

Thermokarst lakes are shallow thaw lakes formed after the thawing of ice-rich permafrost and widely distributed in cold regions with high altitude or latitude [1,2]. Thermokarst lakes show huge differences in lake size ranging from a few square meters to hundreds of square kilometers [6,7,8]. Thermokarst lakes have significantly different geomorphological, physicochemical, and biological characteristics, even at a very small spatial scale [5,9,10,11]. Permafrost degradation continuously drives the evolution of thermokarst lakes in terms of their formation, expansion, shrinkage, and, disappearance [12,13,14]. The fundamental mechanisms of community assembly in thermokarst iations

Objectives

Methods

Results

Conclusion