Because DNA is a tiny molecule found within the cells of living creatures (along with other molecular bits and bobs), you need special tools to pick up it up.
You collect eDNA from water
A common method for collecting DNA is to use a special collection kit that filters water and traps biological material. The DNA can then be extracted from the material captured on the filter in a lab. The kits we provide are made by Wilderlab, and contain a large syringe with a filter that captures particles containing eDNA. Preservative is then injected into the filter capsule to keep the DNA fresh while it is transported to the laboratory for analysis.
The kits are made in Aotearoa New Zealand, and all samples are processed and kept here.
Watch the video on how to take an eDNA sample.
The eDNA is analysed in a lab
Your sample is sent to Wilderlab. There, one of their awesome scientists takes the material trapped on the filter, and extracts and multiplies the DNA using a series of procedures.
Once the DNA is isolated, special molecules called primers are released into the mixture to scan the DNA strands for a unique region called a barcode.
These primer molecules can pick up different things while they are scanning. For example, some will only bring back information on plant DNA, while others are specific to animals. Wilderlab uses a suite of primers they have developed to be especially suited to Aotearoa’s unique flora and fauna, which captures information on fish, insects, birds, mammals, plants and algae.
The barcodes captured are then used to identify different species by comparing the codes to reference databases of known species records.
The eDNA is matched to species
By taking samples of DNA from physical specimens and sequencing their barcodes, scientists know the sequence of components that make up the DNA barcodes of different species. There are databases that convert those DNA barcodes into a list of species.
It is similar to developing a barcode scanner at a supermarket to identify food items. Just like the checkout, we can match the DNA barcodes to species in the database to get a list of all the flora and fauna found in the sample. Not every species will be recorded in a reference database, so sometimes just the type of species the barcode belongs to is identified. This is sometimes referred to as eDNA "dark matter".
It is not uncommon that an eDNA sample will contain this dark matter, and scientists are working on ways to use this data to measure the health of ecosystems without know exactly what the species are.