Dear Ecologist friends who have worked with water or soil eDNA and understand the fundamentals of field data collection, processing and analysis.
I have a few terrestrial species that I would like to target with an occupancy approach, each of them travel through (in transit) water sources, and some are burrowing species. I have a few questions, and please forgive my ignorance I know very little about eDNA other than the core concept.
1. Would eDNA from water samples be an effective means to detect terrestrial species that only transit through water sources?
2. Would soil eDNA be an effective means to detect species that burrow? (i.e. taking the sample directly from a burrow site and BLASTing the metabarcode to match with the target species)?
3. What is the average decomposition rate of eDNA in water and soil? I mean how long could a species presence be detected in water and soil after they have been absent from a given area?
Any discussion is welcome!!
Dear Russell
It's really interesting what you are working in..
I can give you some answers based on our field works..
1. Yes! The release of eDNA is an instantaneous process. We used to quantify, by QPCR, eDNA traces after few seconds of species placing in the aquaria (Yet, I don't know specifically about the situation in streams)..
2. Yes, also..We have preliminary data about eDNA traces from soil burrows made by the redswamp crayfish Procambarus clarkii, which invaded the Nile systen in Egypt. Being the burrows wet or dry, we could detect the species passage there, in its burrows I mean..
3. Don't know exactly the rates of eDNA depletion. I will search for it,that's an excellent concern..
All the best and good luck..
Khaled
Thank you Khaled! This is great news! I'm curious, what in the soil was present to detect crayfish DNA at the burrows? Feces?
You are welcome,Russell. I took samples from crayfish burrows' mud. Actually I couldn't characterize feces visually..
No of course, I mean to obtain the DNA from the mud, something of the crayfish would need to be in it, correct? I was just curious what part of the crayfish shed to obtain their DNA from mud. (sorry I don't know anything about crayfish!)
The decomposition rates of eDNA depends upon the environment in which it is present. It is an interplay of many physical, chemical and biological factors. In sediments eDNA remains well preserved due to anoxic conditions with low and stable temperatures adding to its preservation besides absorption by mineral particles. In sediments and ice cores eDNA has been successfully extracted tracing back to thousands of years.If we take water into consideration eDNA doesn't remain in it for longer periods of time (few days to couple of weeks) because of water turbidity and dilution along the course of flow.
Hope it helps
Thanks & Regards
Zulaykha
Dear Russell Gray ,
In 2019, I came to know about eDNA because one of my friend working in a project which deals with eDNA. Since then I have curiosity and would love to explore it in future. Anyway, I am also a noob in this section but I came across several research in past and hope that might provides you some effective information.
Hope following links might quench your trust.
Article Prospects and challenges of environmental DNA (eDNA) monitor...
Article Factors governing extracellular DNA (eDNA) degradation dynam...
Article Environmental Conditions Influence eDNA Persistence in Aquatic Systems
Thanks!
Best Regards
Ratnesh
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