Kia ora koutou,

Welcome to the latest edition of The Extract, a roundup of recent eDNA highlights, events and resources. In this issue:

• NIWA’s new riverine eDNA sampling guidelines

• The invasion front: monitoring for Corbicula clams and eradicating the fringed water lily

• Celebrating Wai Tuwhera projects in Te Matau-a-Māui

• Searching for skinks in the Southern Lakes Sanctuary

• Looking ahead to the next Australasian eDNA conference in Wellington

New NIWA riverine eDNA sampling guidelines

With local and central government agencies now bringing eDNA into national and regional reporting, it is more important than ever to follow consistent, peer-reviewed, and published methods. Sticking to standardised protocols helps to minimise contamination, maximise sample quality, and build confidence in the assessment of our environmental impacts.

A new set of eDNA guidelines just published by NIWA provides an invaluable resource for both newcomers and seasoned professionals. This comprehensive manual reflects several years of optimisation and validation by the members of the Freshwater eDNA Working Group, including experts from Regional Councils, Ministry for the Environment, the Department of Conservation, NIWA, the University of Waikato, Wilderlab and others.

Key practical guidance provided in the manual includes details on the six-replicate riverine sampling protocol, 1.2 µm vs. 5.0 µm filter pore sizes, active vs. passive sample filtration techniques, an the eDNA prevalence index for fish community monitoring.

eDNA technology is still evolving at pace, and these guidelines will continue to develop in step with advancements in the field. A special thanks to Michele Melchior and Cindy Baker for pulling this all together, WRC’s Josh Smith for the well-designed and executed experiments, and the Envirolink Fund for making it possible. We are proud to have contributed to this resource, and hope you find it useful!

The invasion front:
Corbicula clams and Nymphoides water lilies

Invasive freshwater clams have continued to make a nuisance of themselves, with the golden clam Corbicula fluminea found in the Waikato River in May 2023, and a second species Corbicula australis now discovered in a water park near Taupō. Following the initial discovery of C. fluminea last year, we incorporated a highly-sensitive venerid clam assay into our comprehensive freshwater panel. This versatile metabarcoding assay from Prié et al. 2021 is also capable of detecting other harmful invasive bivalves, including the zebra mussel Dreissena polymorpha and quagga mussel Dreissena bugensis.

Another incursion was thwarted recently when the Mangaone River Catchment Group made a startling discovery in their eDNA results. The group’s eDNA report revealed the presence of the notorious fringed water lily Nymphoides peltata in an isolated pond within the Manawatū-Whanganui region.

This noxious weed has not been seen in Aotearoa since the late 1990s, when it was thought to have been fully eradicated. However, as with many pests, small pockets may go unnoticed in remote locations without regular surveillance.

The group promptly notified Horizons Regional Council, whose biosecurity team acted quickly to eradicate the incursion. This is a nice example of how eDNA can help arm community groups to form a powerful line of defense against environmental threats.

Fantastic work by all involved. You can read more about Mangaone River Catchment Group’s achievement in the Horizons Regional Council press release here.

In early May, the EPA hosted an eDNA wānanga in Te Matau-a-Māui / Hawke’s Bay for communities affected by last year's devastating Cyclone Gabrielle. The event united mana whenua, catchment and community groups, and experts in eDNA and freshwater science. It was a day of shared experiences, learning and reflection, aimed at strengthening place-based relationships and fostering positive outcomes in ongoing restoration and conservation efforts.

The wānanga featured presentations from a diverse group of researchers around the region, including representatives from Ngāti Kahungunu, the Ahuriri Tributary’s Catchment Group, the Ahuriri Protection Society, DOC's Chief Scientist Prof. Mike Bunce, Otago University Profs. Neil Gemmell and Phillip Wilcox, NIWA’s Dr. Shad Mahlum, and our own Freshwater and Community Science lead - Amy Gault.

You can read more about the Cyclone Gabrielle response project and the EPA’s Wai Tuwhera o te Taiao programme here.

Searching for skinks in the Southern Lakes Sanctuary

Some exciting new pilot work is underway by kaimahi at the Southern Lakes Sanctuary Trust, who are trialing eDNA-based methods for monitoring native skink populations. Traditional visual surveys can be challenging due to the steep and expansive terrain and the cyptic nature of the inhabitants. This prompted the team to explore alternative methods to monitor the populations of ‘herpetofauna’ that call the sanctuary home. The SLS team worked with Wilderlab scientists to develop a nifty new lizard-tracking eDNA tunnel, that captures lizard DNA on a filter as they hang out in the hidey-hole. The filter is then sent back to Wilderlab for DNA sequencing using a suite of specialised vertebrate metabarcoding assays.

The results have exceeded all expectations, and the Southern Lakes team now have an effective and reliable monitoring method for these treasured creatures. The team are hoping to share their findings in the form of a research paper later in the year.

We’re excited to be involved in this work and can’t wait to see how this project progresses. You can keep up to date by following the SLS Facebook and LinkedIn pages.

Upcoming Australia and New Zealand eDNA conference

During February 18-21 2025, Te Whanganui a Tara Wellington will host hundreds of eDNA experts and enthusiasts for the 2nd Australian and New Zealand eDNA Conference. The event will be hosted by the newly-formed Southern eDNA Society, and follows on from a fantastic February 2023 conference in Hobart. An emulsion of eDNA scientists, practitioners and community leaders will meet to discuss the latest innovations, share on method development, and highlight some of the remarkable discoveries being made with eDNA.

A great looking line up of session themes have already been announced, and the call for abstracts is now open with submissions due by August 16th. We’re proud to return as the conference's platinum sponsor and would be delighted to see you there.

To stay up to date, you can join the conference mailing list for updates, including notifications for poster and abstract submission deadlines.