Sampling scheme

What is in your sampling kit?

When you first receive the sampling kit, check if you have all equipment you will need. Download the Downloadsampling protocol (PDF, 4 MB)vertical_align_bottom and confirm with the photos on it.

Sampling kit:
- 1x 3L plastic bucket
- 1x Hand suction pump for liquids
- 1x Big plastic bag:
   - 1x Filter cartridge unit with nylon filter
   - 2x Hose (25 cm)
   - 2x pairs of nitrile gloves
- 1x Small plastic bag:
   - 1x pair of nitrile gloves
   - 1x 50 ml plastic tube with 25 ml of preservation buffer
   - 1x 15ml plastic tube lid (red cap)

 

eDNA sampling

DNA is rarely homogeneously distributed in aquatic environments (Lawson Handley et al. 2019, Beentjes et al. 2019, Bewell & Goldberg 2020, Puck et al. 2021). Hence species detection relies on the collection of an adequate number of samples from a water body to capture the heterogeneity of the eDNA signal and be representative of the biodiversity present (Bruce et al. 2021). With a set of over 100 lakes of varying lake area, Sellers et al. (2023) showed that 95% of complete fish richness could be detected with 10 samples around one lake, regardless of lake area.

Sampling environmental DNA from one lake entails the filtration of up to 30 liters of surface water collected from multiple sampling sites along the shoreline. With a maximum of 10 sites distributed around the lake, focus on sampling water from locations in the lake but near the main rivers or streams flowing into the lake and if possible, in the lake near the lake's outflow.
The sampling of the lake water will all be done through a single filter, resulting in one sample per lake, but have water from many locations. The total volume of water to sample should be split across the sites, thus it will be important to have an idea of where you plan to sample before you go. In cases where the lake has less than 10 rivers or streams or accessibility to these points is limited or not allowed (e.g., in a protected area and you do not have a permit to sample), it is perfectly acceptable to sample fewer sites. For example, if the lake has only 2 main rivers flowing into it, the sampling strategy would involve filtering 10 liters of water in proximity to each river and 10 liters near the outflow. If accessibility to the outflow is restricted, sample as close as feasible.

While the recommended sampling volume is 30 liters, it is essential to note that this is an estimate. Instances such as algae blooms or high levels of suspended particles in the water may necessitate a lower filtration volume that must be distributed across all sites rather than focusing solely on one site. In the event of filter clogging, which is experienced when the water flow through the pump is low and it becomes extremely hard to pump the water, simply record the filtered volume obtained to that point.