Environmental <scp>DNA</scp> Based Assessment of Fish Diversity in the Yarlung Zangbo River, Tibetan Plateau

Biodiversity is under unprecedented threat globally, with ecosystems vulnerable to climate change and detrimental anthropogenic impacts. Accurate assessments of biodiversity are essential to the development of effective conservation strategies. We investigated the fish diversity of the Yarlung Zangbo River of the Tibetan Plateau using environmental DNA (eDNA) technology. Water samples collected from 18 sampling sites revealed 18 fish species, including six unique to Tibet and one on China's list of State Key Protected Wild Animals, <i>Oxygymnocypris stewartii</i>. <i>Schizopygopsis younghusbandi</i> is widely distributed, with stable populations in all sampling sites. Non-metric multidimensional scaling analyses showed fish community composition to vary with elevation, although the data did not reach significance. Spearman correlation analyses revealed significant associations of fish species with environmental factors including flow velocity, water temperature, conductivity, and total dissolved solids. Eight exotic fish species were detected, highlighting the potential threat posed by non-native species to the river fish diversity. This study confirms the efficacy of eDNA technology in assessing aquatic biodiversity and its broad applicability as a versatile tool for fish conservation and management, across diverse aquatic ecosystems. In contrast to traditional methods, eDNA offers a non-invasive, simpler, and more efficient approach for detecting a broad range of species, including those that are rare or difficult to capture. The findings emphasize the need for future research to integrate traditional survey methods and eDNA technology to comprehensively assess ecosystem biodiversity and develop targeted conservation strategies.