One observant horse rider, a few photographs, and a quick call to DOC have led to the discovery and removal of 141 invasive sea spurge plants from Ninety Mile Beach.
What initially appeared to be a handful of unusual plants along the beach near Lone Pine, north of Ahipara, turned out to be a significant infestation of sea spurge (Euphorbia paralias), an invasive coastal weed that can threaten New Zealand’s native dune ecosystems.
The rider, recalling information they’d previously seen about sea spurge, stopped to take photographs, recorded the GPS location and reported the find.
DOC Sea Spurge Ranger James Gardner says the discovery is a fantastic example of how everyday New Zealanders can make a real difference to conservation.
“This is exactly why we encourage people to keep an eye out for unusual plants when they’re enjoying our beaches.
Close up of sea spurge plant
Image: DOC
“One person noticed something that didn’t look quite right, and took the time to report it. That simple action led us to an infestation that might otherwise have gone unnoticed.”
Sea spurge is native to Europe and can form dense infestations that crowd out native coastal vegetation. It is likely to have arrived on ocean currents from Australia but is not yet established in New Zealand, so every plant found and reported helps to prevent sea spurge displacing native plants and changing natural patterns of sand movement.
The find prompted a rapid response involving Biosecurity New Zealand (who manage the sea spurge programme), DOC, Northland Regional Council, and local ecological expertise, with a team on site the following day.
What they found was more extensive than the initial photographs suggested.
Hidden among the shifting dunes were mature and flowering sea spurge plants, young plants and dozens of tiny seedlings.
In total, the team located and removed 141 plants – 5 mature adults, 14 juveniles and 122 seedlings.
“The really concerning part was finding the mature plants had already produced seed,” James says.
“Sea spurge can spread along coastlines, so finding it early and removing plants before they spread further is really important.”
The location presented some unusual challenges. The infestation was tucked into an active sand drift, where moving sand had buried vegetation and almost completely covered some of the mature sea spurge plants.
The shifting landscape may explain why the infestation had escaped detection during previous surveys.
Although all visible plants were removed, the job isn’t finished.
Sea spurge seeds can remain viable in the sand for several years, meaning more plants could emerge from seeds already buried at the site. Ongoing monitoring and follow-up control will be carried out to ensure the plants don’t establish.
James says the find is also a timely reminder that biosecurity isn’t just the responsibility of conservation staff.
“We can’t be everywhere, and our coastline is enormous. People out naturing can be our extra eyes on the ground, whether they’re out walking their dogs, fishing, riding horses or simply enjoying the beach.
“The person who reported this find did everything right. They took photos, recorded the location and let us know. We’d love more people to do the same.”
If you suspect you have found sea spurge, don’t touch it, as it contains a toxic milky sap that can irritate skin and eyes. Sea spurge can be confused with other coastal plants, including the nationally rare native shore spurge, so people should avoid touching or removing suspicious plants themselves.
“If you see something that looks like sea spurge, take a photo and report it. You never know – your discovery could help protect an entire stretch of coastline,” James says.
Think you’ve spotted sea spurge?
- Take clear photographs of the plant.
- Record the GPS location or a description of where you found it.
- Don’t touch or remove the plant – its sap can cause skin and eye irritation.
- Report suspected sightings to DOC on 0800 DOC HOT (0800 362 468).
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