Thanks to Tracy Gill and Katharine Egan, Mark Stoeckle and Jesse Ausubel gave a NOAA-wide “Omics” seminar. 29 October 2021. Title and abstract are below. View the recording of the webinar via Adobe Connect, here: https://noaabroadcast.adobeconnect.com/pnnos0mcsh3z/ Thanks to the attendees for lotss of great questions and the lively to-and-fro in the Chat Box.
Abstract: Measuring quantities of eDNA is fast becoming a preferred method of learning the presence and abundance of fish and other aquatic species. But how much water need one filter and how much DNA need one process to obtain a reasonably complete and reproducible answer? Tests of an eDNA metabarcoding protocol for marine bony fish show more water, more species of fish up to levels tested. Amplifying decreasing amounts of extracted DNA yields progressively fewer species. Species represented by more copies (reads) of their DNA are detected more reproducibly and with less variation than lower-read species. Findings are consistent with Poisson distribution of rarer eDNA. We also vary PCR cycles, sequencing depth, primer concentrations, and primers. Our findings have multiple practical implications, including for survey strategies for both common and rare species, and identify some limits of knowledge and research directions for aquatic eDNA science.