基于古DNA重建的青藏高原中部错鄂湖浮游生物变化历史及其驱动机制研究

Most studies about paleo-plankton only focus on identified microfossil plankton. However, the majority of plankton do not have fossilizing microscopic feature, and are thus excluded from micro-palaeontological observations. Ancient DNA of sediments could record much more complete information about past plankton community structure than microfossil. Moreover, research on how the ancient plankton responded to certain period (little Ice Age, modern global warming) still remains in its infancy. Tibetan Plateau are very sensitive to climate change, we thus selected the Tso Ur Lake located at the boundary region between Monsoon and Westerly to investigate the modern process and shift history of plankton community during last hundreds of years. We plan to sample the plankton of lake water regularly during the growing season and study the environmental factor driving the change of plankton community. Meanwhile, we will drill several gravity cores to reconstruct plaeoplankton community structure and number (based on palaeoenvironmental DNA analysis), paleotemperature（based on alkenones analysis）and paleohydrology (based on granularity analysis). Finally, based on the comparison of multiple index from one same core and modern process, we plan to investigate the driving mechanisms of climate change on plankton community during past hundreds of years in Tso Ur Lake, and provide referring information to predict changes of lake ecosystem to climate change in the future.

目前多数古浮游生物研究只关注有可鉴定微体化石的种属，但大多数浮游生物种属因缺乏微体化石而难以被研究。沉积物DNA则可记录更为完整的浮游生物群落信息,而且关于浮游生物如何响应一些特征气候变化期（如小冰期、近代全球变暖期）的认识还很薄弱。青藏高原对全球气候变化响应十分敏感，本研究选择青藏高原中部处于季风-西风边界区的错鄂湖为研究对象，拟开展浮游生物现代过程以及变化历史重建研究。首先，通过采集生长季不同时段湖水浮游生物样品，研究短尺度浮游生物种群变化及其驱动因素；其次，采集多根重力钻，对其开展古浮游生物群落（基于古DNA方法）、古温度（长链烯酮指标）及古水文（粒度等指标）重建；最终，基于同钻孔多指标对比，并参考现代过程研究结果，探讨错鄂湖近几百年浮游生物种群变化的气候驱动机制，为预测未来湖泊生态系统变化提供参考资料。

沉积物古DNA可记录更为完整的浮游生物群落信息，现已成为促进湖泊古生态研究的重要方法。本项目主要从历史演变的角度，基于沉积物古DNA技术探讨了湖泊浮游生物种群演变历史及对历史气候变化的响应机制。主要取得如下三方面成果：（1）分析了错鄂湖钻孔沉积物多指标，系统重建了过去两百多年来湖泊浮游植物和真核微型生物群落与环境演化历史。（2）基于多种统计方法，揭示出错鄂湖浮游植物和真核微型生物的生物多样性变化、稳态转换动态特征和驱动机制。（3）基于古DNA研究揭示在受风尘沉积影响的地区，尘埃输入可以超过自然气候的变化，而成为控制湖泊生态系统的主要因素；低地湖泊中潜在的有毒蓝藻随着气候变化而增加。该项目推动了利用沉积物古DNA方法恢复历史时期无微体化石的湖泊浮游生物的古生态学研究，使其呈现出更完整面貌的湖泊古生态系统变化，促进了在我国青藏高原及其他区域湖泊古生态研究，为湖泊水生态健康和评估提供了新的视角和科学依据。