eDNA sampling strategy

One of the key aspects of an eDNA analysis is the eDNA sampling strategy. By employing the appropriate eDNA sampling strategy, a success rate of 95% can be achieved. Sylphium has developed materials based on the guidelines outlined in NPR 73 94, which enable rapid and highly reliable collection of samples.

Sampling

An important part of the sampling is the determination of the place of sampling in order to maximise the chance of capturing DNA from the target organism. In doing so, the ecological wishes of the organism to be determined must be taken into account. The chance of detection of a species can be greatly increased by taking multiple samples in different places in one water body. DNA is quickly broken down (within 2 days at a water temperature of 20 degrees Celsius). The whole procedure and tips are explained in the protocol beloning to environmental sampling set.

Sylphium’s eDNA analysis offers the highest possible sensitivity (1 molecule per analysis). The eDNA sampling strategy has the greatest impact on the success rate of the method.

To achieve maximum success rate without eDNA cross-contamination between samples and ensuring proper sample registration, the following basic sampling rules (based on literature and experiments) should be followed:

• Use an absolute minimum sample volume of 0.75 liters. eDNA is present in low concentrations in water, and a large volume is necessary for sampling. If the eDNA Dual Filter Capsule becomes clogged before reaching the minimum sample volume, a second eDNA Dual Filter Capsule can be used and later combined in the lab and analyzed as one sample.

• Take a new sample every 300 meters. eDNA dispersion in water is limited, so it is necessary to plan for a new sample every 300 meters.

• A sample consists of sub-samples. Ideally, sub-samples should be taken every 10 meters along the shore to bridge the distance between two samples. Sub-samples of 60 ml can be easily taken with the sampling kit and immediately filtered.

• Sample in the preferred niche. Samples should be taken in the preferred niche to increase the success rate as much as possible.

• Sample in the appropriate season. Many organisms are not present in the water or at a particular location all year round. This should be taken into account during sampling.

The sampling kit’s accompanying manual contains more recommendations and information.

eDNA sampling kit

Sylphium Molecular Ecology developed a specialized sampling kit to collect water samples for eDNA analysis actively. The kit allows for filtering water samples on-site with a filter unit, which minimizes contamination risks and requires relatively little equipment for sampling and filtration in the field. The sampling kit includes an eDNA Dual Filter and a 60 ml syringe, enabling the sampler to take a water sample without direct contact with the water. The filter unit is placed on the syringe, and the water is pressed over the filter unit, without the need for a vacuum pump. After adding the preservation fluid and sealing the filter unit with the included caps, the sample can remain stable for several weeks to a few months without refrigeration. The filter unit, with a unique sample number, can be shipped unrefrigerated by post to the laboratory of Sylphium Molecular Ecology for further analysis. Customers can order sampling kits from the webshop, and the price of the sampling kit will be deducted from the analysis fee.

Sampling rod

Sylphium molecular ecology developed a specialized sampling rod that allows the collection of water samples in difficult-to-reach areas, such as overgrown and deep banks. The sampling rod holds a 60 ml sterile disposable injection syringe (from the sampling kit) for collecting water samples. This eliminates the need for waders, protective suits, a boat, or other tools to collect water samples and speeds up the sampling time significantly. After sampling, users can replace the injection syringe, and the sampling rod is ready for use again. Sylphium molecular ecology offers the sampling rod for purchase separately, which can be ordered through the shop.

Sending samples

After sampling, the filtered water sample is sent unrefrigerated in the eDNA Dual Filter to the lab of Sylphium molecular ecology. The eDNA Dual Filter is put back in the bag of the sampling set with a unique sample number for shipment. Based on this number, the sample can be identified afterwards. The samples can be shipped (registered) via Postnl to:

Sampling