Urgent Call to Action: Invasive aquatic weed surfaces in local ponds

Plant pest fringed water lily (Nymphoides peltata) - thought to have been eradicated from NZ - has been found in the Horizons Regional Council area during routine water testing using the eDNA sampling method.

Opinion

By Gwyn Jones, Manawatu River Catchment Collective

Nymphoides peltate (Fringed water lily, also known as Entire marshwort, yellow floating heart has been found in the Mangaone catchment.

Thought to have been eradicated in 1998, as part of its catchment work a recent eDNA test indicated its presence and we need your help to stop it from spreading.

We are asking people to check their ponds for any unusual lilies or plants growing that have never been seen before.

Additional testing and site visits confirmed its location, leading Horizons Regional Council to bring in respected scientist and aquatic weed specialist Dr Paul Champion.

Dr Champion advised how best to deal with the lily and suggested eradication plans. (Coincidentally it was Dr Champion who had previously registered the weed on the eDNA database, which triggered the catchment picking up its presence)

While native in the UK, and its original spread from deliberate plantings, the origin of the lily in the Tararua District is unknown, and why we need the help of the local community. The weed poses a high risk of dispersal, and our freshwater does not need more invasive species.

Its unchecked growth can choke water bodies, outcompeting natives, and disrupting ecological balances. Swift action is imperative to preventing its further spread.

The good news is, Horizons was proactive in dealing with this problem, allocating funding and tackling the issue head-on. Their view was this was an opportunity to eradicate the plant before it became a real problem. Under Dr Champion’s guidance, the council proceeded to take the water away from the plant, disestablishing the pond in a way that didn’t cause any potential contamination or spread.

The value of catchments

The discovery of the weed underscores the valuable role of community engagement in environmental stewardship.

Equally, the collaboration between the Catchment group and Horizons serves as a reminder of the power of collective action.

Horizons would not have found this plant if it had not been for the Catchment group testing streams.

Jack Keast senior biodiversity officer – plants says: “We weren’t even looking for it, it’s not our hit list, as it is recorded as eradicated. This find really does highlight the value of catchment groups addressing challenges related to water management and ultimately helping communities enhance and protect their local environments”.

What can you do?

By keeping a watchful eye on ponds and water bodies, individuals can also contribute significantly to early detection and containment efforts.

If you suspect Nymphoides peltate presence in your area or require further information, contact:

Jack Keast senior biodiversity officer – plants E: Jack.Keast@horizons.govt.nz or the Horizon’s biosecurity plants team on 0508 800 800. The team can come and check ponds if you are concerned you may have this plant.