The effect of silica desiccation under different storage conditions on filter-immobilized environmental DNA.

While the detection of relatively abundant eDNA target was stable over 15 months from either ethanol- or silica gel-preserved filters at - 20 and 4 °C, silica gel out-performed ethanol preservation at 23 °C by preventing a progressive decrease in eDNA sample quality. Silica gel filter desiccation preserved low abundance eDNA equally well up to 1 month regardless of storage temperature (18, 4, or - 20 °C). However only storage at - 20 °C prevented a noticeable decrease in detectability at 5 and 12 months. The results indicate that brief storage of eDNA filters with silica gel beads up to 1 month can be successfully accomplished at a range of temperatures. However, longer-term storage should be at - 20 °C to maximize sample integrity.