Abstract
The amalgamation of global climate change, escalating anthropogenic activities, and species invasions has resulted in a decrease in the biodiversity of aquatic organisms. The Batanghari River, one of Indonesia's longest rivers, is impacted by anthropogenic activities including pollution from mercury-containing waste originating from illegal gold mining (PETI), industrial pollutants, and domestic waste. Studies have highlighted a decrease in organismal biodiversity within the river, yet a comprehensive assessment of its current status is lacking. eDNA metabarcoding is a promising tool for understanding biodiversity of river affected by anthropogenic pollution, offering broader insights compared to traditional methods. We used eDNA metabarcoding to analyze biodiversity distribution in the Batanghari River, yielding 22,180,436 reads from 405 eDNA samples across 5 locations and 15 sites. Significant variations in beta diversity were observed among locations. Approximately 80% of reads were classified to the species level, with the remainder identified as unidentified taxa. Our findings underscore disparities in species richness and community composition between upstream and downstream areas, likely influenced by anthropogenic stressors. This method revealed the presence of several extinct and endangered species at multiple sampling locations. Understanding species diversity and distribution is crucial for advancing river ecology and conservation practices.