Geology topics

Austen Thomas

Publications and source records attributed to Austen Thomas.

3 recordsLinked to original sources

USGS2025

Field test of the self-preserving eDNA filter and the importance of calibration when changing methods during long-term monitoring

Filtering water is currently the primary field method used for collecting aquatic environmental DNA (eDNA). One of the drawbacks of filtering is the need to transfer the filter from the filter housing to a preservative-filled container in the field. New products are being developed to avoid this handling step, but comparative studies are needed to ensure that the results produced by new protocols are transferable within and across eDNA monitoring programs. To meet this need, we evaluated two filter preservation methods (self-preserving filter housing vs. ethanol) of the 5.0-μm polyethersulfone (PES) filter membrane in a field trial typical of stream fisheries eDNA sampling. We compared DNA detection and yield for free-swimming rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), from streams in Washington, United States, and British Columbia, Canada, while accounting for the effects of two environmental covariates: stream discharge and water temperature. As these streams were part of an ongoing fisheries eDNA monitoring program, we also compared these methods to the original protocol, which used a 0.45-μm cellulose nitrate (CN) filter membrane and ethanol preservative. We found that the self-preserving filter housings collected and preserved eDNA well and provided similar results to identical filters preserved in ethanol. The 5.0-μm PES filters preserved in ethanol significantly outperformed the original protocol in terms of both DNA detection and yield, highlighting the importance of calibration of eDNA results when changing sampling methods during an ongoing monitoring program.

british Columbia, Washington↗

USGS2024

Field trials of an autonomous eDNA sampler in lotic waters

Environmental DNA (eDNA) analysis has become a transformative technology, but sample collection methods lack standardization and sampling at effective frequencies requires considerable field effort. Autonomous eDNA samplers that can sample water at high frequencies offer potential solutions to these problems. We present results from four case studies using a prototype autonomous eDNA sampler as part of the U.S. Geological Survey’s Rapid Environmental eDNA Assessment and Deployment Initiative & Network (READI-Net) project. These case studies involved short-term deployments of an eDNA autosampler (Smith-Root) across a range of riverine habitats with the objectives of (a) identifying what insights could be gained from high-frequency autosampling and (b) benchmarking these autosamples against manually collected samples. The high frequency autosampling revealed high temporal variability of eDNA concentrations and provided valuable insights about eDNA associations with environmental covariates, such as discharge and turbidity. Benchmarking assessments indicated autosamples had similar detection rates to manual samples and obtained similar or greater eDNA quantities. We did find minimal carryover contamination in autosampler field controls. We conclude that eDNA autosamplers have potential to improve freshwater biosurveillance by reducing logistical sampling barriers, standardizing collection methods, and clarifying the influence of environmental covariates on eDNA results.

Idaho, Missouri, Montana, New York↗

USGS2023

Toward a national eDNA strategy for the United States

Environmental DNA (eDNA) data make it possible to measure and monitor biodiversity at unprecedented resolution and scale. As use-cases multiply and scientific consensus grows regarding the value of eDNA analysis, public agencies have an opportunity to decide how and where eDNA data fit into their mandates. Within the United States, many federal and state agencies are individually using eDNA data in various applications and developing relevant scientific expertise. A national strategy for eDNA implementation would capitalize on recent scientific developments, providing a common set of next-generation tools for natural resource management and public health protection. Such a strategy would avoid patchwork and possibly inconsistent guidelines in different agencies, smoothing the way for efficient uptake of eDNA data in management. Because eDNA analysis is already in widespread use in both ocean and freshwater settings, we focus here on applications in these environments. However, we foresee the broad adoption of eDNA analysis to meet many resource management issues across the nation because the same tools have immediate terrestrial and aerial applications.

Environmental DNA↗