Warming reduces microeukaryotic diversity, network complexity and stability.

Unraveling how climate warming affects microorganisms and the underlying mechanisms has been a hot topic in climate change and microbial ecology. To date, many studies have reported microbial responses to climate warming, especially in soil ecosystems, however, knowledge of how warming influences microeukaryotic diversity, network complexity and stability in lake ecosystems, in particular the possible underlying mechanisms, is largely unknown. To address this gap, we conducted 20 mesocosms spanning five temperature scenarios (26 °C, 27.5 °C, 29 °C, 30.5 °C, and 32 °C) in Lake Bosten, a hotspot for studying climate change, and investigated microeukaryotic communities using 18S rRNA gene sequencing. Our results demonstrated that warming, time, and their interactions significantly reduced microeukaryotic α-diversity (two-way ANOVA: P＜0.01). Although warming did not significantly affect microeukaryotic community structure (ANOSIM: P＞0.05), it enhanced species turnover. Microeukaryotic networks exhibited distinct co-occurrence patterns and topological properties across temperature scenarios. Warming reduced network complexity and stability, as well as altered species interactions. Collectively, these findings are likely to have implications for ecological management of lake ecosystems, in particular semi-arid and arid regions, and for predicting ecological consequences of climate change.