Evaluation of An Environmental DNA Procedure for the Detection of New Zealand Mudsnails

New Zealand mudsnails (NZMS) are an invasive species that were first introduced to North America in 1987.  Since their initial finding in Idaho, the range of NZMS has spread to include the entire western portion of the United States and Canada, and many other locations throughout the continent.  New Zealand mudsnails can achieve a high abundance, compete with native invertebrates, and can disrupt ecosystem function.  The NZMS is small and the traditional detection procedure for NZMS requires a time consuming, extensive visual search of a habitat.  Recently, an alternative detection approach that entails the recovery of NZMS DNA from filtered water samples was developed.  In this presentation, I will describe several studies that have been conducted to  ground truth and evaluate this eDNA detection procedure.  First, I will describe our sampling apparatus.  Next, I will describe laboratory studies that show that a relationship exists between NZMS density and the number of NZMS DNA fragments amplified during PCR.  These laboratory studies also show that the discharge of DNA by NZMS does not demonstrate diel variation nor does it vary with day.  Finally, I will describe field trials that show that the NZMS eDNA procedure works in a variety of habitats including small creeks, larger rivers, lakes, and ponds.  The results show that the eDNA procedure is highly sensitive for the detection of the snail.  Based on these findings, it appears that this eDNA approach is a simple, quick method for the detection of NZMS.