Distinct multitrophic biodiversity composition and community organization in a freshwater lake and a hypersaline lake on the Tibetan Plateau

Alpine lakes play pivotal roles in plateau hydrological processes but are highly sensitive to climate change, yet we lack comprehensive knowledge of their multitrophic biodiversity patterns. Here, we compared the biodiversity characteristics of diverse taxonomic groups across water depths and in surface sediments from a freshwater lake and a hypersaline lake on the northwestern Tibetan Plateau. Using multi -marker environmental DNA metabarcoding, we detected 134 cyanobacteria, 443 diatom, 1,519 invertebrate, and 28 vertebrate taxa. Each group had a substantially different community composition in the two lakes, and differences were also found between water and sediments within each lake. Cooccurrence network analysis revealed higher network complexity, lower modularity, and fewer negative cohesions in the hypersaline lake, suggesting that high salinity may destabilize ecological networks. Our results provide the first holistic view of Tibetan lake biodiversity under contrasting salinity levels and reveal structural differences in the ecological networks that may impact ecosystem resilience.