Environmental DNA (eDNA) has become a popular biological survey tool, but its potential as a tracer of water and sediment transport remains underexplored. Understanding how eDNA signals are generated, mobilized, degraded, and preserved in water is essential not only for tracking biodiversity, but might reveal flow paths, residence time, sediment origin, and connectivity across hydrological and geophysical systems. This session is dedicated to exploring eDNA as a tracer of transport, discussing it alongside the established toolkit of hydrological tracers, including stable water isotopes, hydrochemistry, and particles such as fluorescent microspheres, bacteriophages, and spores. Recent work has demonstrated the feasibility of using eDNA to characterize flow paths and catchment response in Alpine and urban systems, and of incorporating eDNA sampling directly into hydrological monitoring and time series studies. Our primary focus is on recent-time eDNA signals in freshwater and surface waters, but we also welcome contributions that link present-day eDNA patterns to longer-term records preserved in sediment archives. Beyond rivers, we are interested in studies from wetlands, groundwater, and even lakes, coastal waters, and oceans.

Presentations in this session will address the methodologies, applications, and implications of eDNA for understanding the movement, persistence, and transformation of genetic tracer material within hydrological and geophysical systems. We encourage contributions that investigate how eDNA distribution is shaped by transport mechanisms, degradation kinetics, and environmental drivers such as flow, sediment, and biogeochemistry and what that knowledge can reveal about the underlying physical processes. Studies that integrate laboratory analyses, modeling, or sediment archives to connect scales and processes are particularly welcome. We also seek contributions that push the boundaries of how eDNA is observed. This includes innovative sampling strategies such as custom-built sensors and passive samplers, automated or distributed collection networks, and citizen science approaches that expand the spatial and temporal characterization of eDNA signal transport, concentration, and decay. By bringing together diverse systems and approaches, this session aims to advance eDNA as a tool for tracing physical transport processes, fostering new interdisciplinary collaborations between hydrology, sedimentology, and molecular methods.