eDNA REVEALS PHYTOPLANKTON COMMUNITY ASSEMBLY MECHANISMS AND SEASONAL DYNAMICS IN THE MIDDLE REACHES OF THE YARLUNG ZANGBO RIVER

Phytoplankton, as a key and sensitive component of plateau river ecosystems, remains understudied in the middle reaches of the Yarlung Zangbo River regarding its species composition, seasonal dynamics, and particularly the mechanisms of community assembly and their responses to environmental factors. This study employed environmental DNA (eDNA) to systematically analyze the diversity, seasonal dynamics, and driving mechanisms of phytoplankton community in the middle reaches of the Yarlung Zangbo River. A total of 25 sampling sites were established, with water samples collected during both wet and dry seasons. Sequencing results identified six phytoplankton phyla, with Ochrophyta (57.65%) and Chlorophyta (32.42%) being the dominant groups. α-diversity analysis revealed no significant seasonal differences in Simpson and Shannon indices, while the Chao1 index was significantly higher during the dry season than the wet season (P