Unknown, distinct, and in danger: Planktonic communities in lakes of the Tibetan Plateau under the threat of climate change

As the foundation of lake ecosystems, the planktonic communities on the Tibetan Plateau have been severely affected by rapid climate change. However, fully understanding their diversity, taxonomic composition, functional traits and ecological interactions, as well as clarifying how they respond to climate change, remains a major and understudied challenge in ecology. During a five-year expedition on the Tibetan Plateau, we sampled prokaryotic and eukaryotic plankton from 95 lakes, encompassing the > 0.2 µm, 0.2–3.0 µm, and > 3.0 µm size fractions, thereby mapping previously unknown and distinctive planktonic profiles. We also explored the processes underlying the biogeographical patterns of planktonic communities and determined that temperature and salinity are key deterministic factors. Moreover, climate change affected plankton communities both directly and indirectly, threatening their interactions, stability, and functioning. Based on lineage-specific temperature and salinity niche ranges, our scenario-based analyses project substantial climate-associated declines in planktonic lineage richness across Tibetan Plateau lakes by 2100, without effective climate-policy interventions. Planktonic communities on the Tibetan Plateau may face an elevated risk of abrupt reorganization as early as the 2040s under climate-driven stress, suggesting that the climate “time bomb” for these lake ecosystems may already be ticking. Our work, which is based on the most comprehensive empirical evidence available to date, highlights the severe threats to planktonic biodiversity in lakes on the Tibetan Plateau under climate change, providing crucial early warnings and informing conservation decisions for lake ecosystems globally.