Knee-deep in healthy rivers: Rees Valley Station farmer Kate Scott takes samples as part of an eDNA water sampling project

A water sampling project using new environmental DNA (eDNA) technology has revealed 12 out of the 13 tributaries of the Rees River tested are pristine.

The project was started last year by Southern Lakes Sanctuary (SLS), Rees Valley Station’s Iris and Kate Scott and Temple Peak Station’s Amanda Hasselman, to understand what species occupy the Rees Valley ecosystem.

Part of the species mapping hoped to reveal if whio, which haven’t been seen in the area since the ’60s, were inhabiting remote parts of the valley — and if they weren’t, whether it would be safe to re-introduce them, SLS co-chair Leslie Van Gelder says.

The eDNA sampling, which collects genetic material shed by organisms via a drogue which filters water through a sponge, was a simple way of finding out.

‘‘It’s kind of like the same way they find Covid in the water — they can test for anything that has left DNA in the water,’’ Van Gelder says.

What would’ve traditionally been a manpower-heavy exercise was greatly simplified by the new technology and, supported by funding from a GY community member, the group was able to test 13 waterways in the Richardson Ranges branch of the Rees Valley.

Although they didn’t find any whio, the samples revealed all but one of the waterways tested are as clean as can be.

While the absence of whio DNA was a dampener, the similar lack of ferret and feral cat DNA means SLS can move on its plan to re-introduce the native duck to the valley.

‘‘If we have an area that we can say, ‘well, the eDNA’s saying there are no ferrets, and our traps are showing there are no ferrets’, we can
then feel more confident going to the species reintroduction teams and go … ‘we’re a good candidate as a site’.’’

For Hasselman, who’s also a Routeburn Dart Wildlife Trust trustee, the results help her understand the impact farming has on the ecosystem.

‘‘I think we’re starting to realise that, while we’ve talked a lot about carbon, biodiversity is the key thing moving forward, and how we can
farm alongside biodiversity.

‘‘The beauty of this whole project is just the really cool synergy between farmers and the community, the [SLS] trust and private individuals who are interested in advancing what’s going on up there.’’

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