Developing Feasible Methods for Incorporating eDNA Sampling in Hydrological Time Series Studies

ABSTRACT

Environmental DNA (eDNA) is emerging as a promising hydrological tracer, complementing its established role in ecological monitoring. Here, we develop a feasible and easily realisable method for including eDNA sampling in automated hydrological time‐series sampling. The 3D printable and reusable frames, appropriate for common filter membranes, passively sample eDNA in triplicate replication. The influence of the frames on other hydrological parameters, such as the composition of ions and organic matter, was assessed, as well as the impact of standing time. No significant influence on water chemistry measurements could be detected through the presence of eDNA passive samplers. As expected, the impact of standing time could be observed for both biodegradable parameters, organic matter and eDNA. Simultaneously, an increase in total DNA content was observed over time, probably related to biofilm growth. Surprisingly, the concentration of a spike fragment stabilised after 24 h of exposure to sampling water and remained at that level even until 7 days of exposure to sampling water. Biofilm formation could play a role in this stabilisation of free eDNA over longer periods. Due to the reusability and adaptability of the 3D printable frames, there is no need for additional devices to integrate eDNA sampling. Our results show that passive eDNA sampling can be seamlessly integrated into automated hydrological time series monitoring by simultaneously sampling the composition of ions and organic matter and, under certain limitations, e.g., the use of microbial communities, even if several days of standing times are necessary. The adaptability of the frame to various membrane formats and the reusability of the model make it broadly applicable in research and applied cases.