Time
We determined that long submersion times are not necessary for passive
eDNA collection and effective sampling can be achieved in as little as
five minutes. Conventional eDNA filtration methods are time consuming,
especially when considering the amount of water needed to effectively
filter an area for accurate biodiversity estimates (Bessey et al. 2020,
Koziol et al. 2019). A quick eDNA collection method would have
considerable benefit for end users and increase sampling capacity.
Increased sampling capacity enables a broader range of ecological
question to be addressed through comparative frequency analysis
(Strickland et al. 2019), which are more powerful with larger sample
sizes. Therefore, exploring the minimum amount of time required for
passive eDNA collection membranes to saturate would be a worthwhile
endeavour to maximize efficiency. In laboratory experiments, Kirtane et
al. (2020) found no difference in adsorbed extracellular DNA
concentrations over a time gradient between one min to two hours for
granular active carbon in tank water, but that differed in creek waters.
These previous studies indicate that site specific water chemistry
affects the effectiveness of passive eDNA collection. Therefore, a
better understanding of the mechanism of eDNA adherence to materials
could help optimize passive eDNA collection methods.