Starsha Bird1, Dr Ang McGaughran1
1University Of Waikato, Hamilton, New Zealand
Environmental DNA (eDNA) sampling methods are well established in riverine systems. However, eDNA use in wetland environments is still in its infancy because wetlands pose a series of challenges for eDNA techniques. For example, high sediment volumes can impact filtering, reducing the total volume of water than can be processed. The primary objective of our research was thus, to optimise eDNA sampling by testing different field techniques and exploring the spatial and temporal variability of eDNA in the context of wetlands.
We sampled four spatially-distant sites across Opuatia Wetland (Waikato, Aotearoa, New Zealand), at three time points during September – November 2022. At our main sampling site, we also tested three different filter sizes (1.2μm, 5μm, 25μm) and different volumes of water (1L, 100L) to evaluate the impact of these parameters on DNA detection. Alongside eDNA samples, we collected data from fish traps, aquatic microfaunal samples, and 5-minute bird counts for comparison. In a separate experiment, we introduced foreign DNA at our main sampling site and then sampled at different time points post-release, over three distances (1m, 10m, and 25m away from the release point) to determine the residence time of DNA in wetlands.
Ultimately, our assessment will result in an efficient eDNA sampling protocol for wetland environments that will support restoration groups and other agencies who wish to monitor wetland health and dynamics. This will be particularly important in Aotearoa, where < 10% of wetlands remain, and ongoing restoration and monitoring are of critical importance.
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