Thesis
Physical Processes and the Dispersion of Environmental DNA in Ponds: Experiments to Inform the Detection of Rare Amphibians
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005019
Abstract
Ponds provide habitat for many rare and endangered freshwater species and are focal areas for conservation and species monitoring efforts. Environmental DNA (eDNA) analysis can provide an effective way to detect and monitor pond species, but the application of this method is limited by the lack of knowledge on eDNA transport dynamics in these systems. Low flow velocities in ponds lead to short dispersion distances and the heterogeneous distribution of eDNA. This leaves areas within occupied ponds void of eDNA, presenting the predicament of false negative results. Physical processes in ponds likely play important roles in the horizontal and vertical transport of eDNA but these have not been characterized in ponds. To investigate how eDNA is transported in ponds, we conducted field experiments to measure the distance and direction eDNA traveled from a small number of amphibians (blotched tiger salamanders: Ambystoma mavortium melanostictum) contained at a fixed point. During these experiments, we measured water movement and temperature at high resolution using acoustic Doppler current profilers (ADCPs) and vertically stacked temperature loggers and recorded wind velocity onsite using a wind meter. We found that eDNA in our system was detected ≤20 m from the source and that detection probability at the pond surface was reduced by the presence of aquatic macrophytes at the sampling site and increased distance from the source. We also found that detection probabilities were higher when the epilimnion was thinner and samples were collected upwind of the enclosure. Pond turnover may have increased detection rates by resuspending eDNA preserved in the aphotic layer. The relationship between hydrodynamics and eDNA is complex and the state of eDNA and pond conditions will influence the distance and direction eDNA is transported in the system. Additionally, the size and buoyancy of eDNA particles will affect how wind influences their dispersion patterns and surveys may want to include sampling points in the upwind and downwind locations on windier days. We recommend that eDNA surveys for rare amphibians consider these physical processes and vegetation structure in relation to the habitat use and daily activity patterns of the target species when determining sampling design.
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Details
- Title
- Physical Processes and the Dispersion of Environmental DNA in Ponds
- Creators
- Sandra Mayne
- Contributors
- Caren S Goldberg (Advisor)Jeffrey A Manning (Committee Member)Stephen M Henderson (Committee Member)Jenifer K McIntyre (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 96
- Identifiers
- 99901019634701842
- Language
- English
- Resource Type
- Thesis