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Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
environmental DNA, eDNA, qPCR, lotic, stream
Recent years have seen an explosion of interest in the use of freely available DNA present in aquatic systems, otherwise known as environmental DNA (eDNA), as a tool for monitoring aquatic organisms. However, much remains unknown about the behavior of eDNA over a range of environmental conditions. This is particularly true in high gradient headwater streams, which have received less attention than other types of water bodies. In the summer of 2011, a headwater stream system with well established species distributions was sampled using eDNA techniques. Though species were detected where known to be present, detections also occurred where traditional techniques failed to detect species. This suggests that a cautious approach to positive eDNA detections is advisable. In 2012 a second study was conducted to better understand the dynamics of eDNA concentration in lotic systems. Caged brook trout (Salvelinus fontinalis) were introduced into two otherwise fishless headwater streams, and eDNA samples were collected at evenly spaced intervals downstream of the cage. This was repeated 19 times from mid-summer through autumn, over flows ranging from approximately 1 to 96 l/sec. Quantitative PCR was used to relate DNA copy number to distance from source for each of these 19 sampling events. In all cases, DNA was detectable at 239.5 m from the cage. Increasing flows generally decreased eDNA copy number near the cage but had relatively little effect at downstream sites. Additionally, the presence of leaf biomass during the fall period had the potential to completely erase otherwise high DNA levels.
Andrew R. Whiteley