Sea Spurge, Euphorbia paralias
Sea spurge is a seaside-loving perennial herb, found growing on dunes, cliffs, and sandy beaches. It has multiple stems, often reddish at the base, and leaves that are blue-green. In Aotearoa, sea spurge is classified as an Unwanted Organism, and if left unchecked, could have serious impacts on our coastal ecosystems.
Native range: North Africa, western Asia, and Europe
Arrival in Aotearoa: Sea Spurge seeds arrive on ocean currents from Australia, where it is also invasive. Stems and seeds are spread easily via the elements and sometimes with our (unintentional) help.
Coastal takeover: Plant communities play a big role in shaping our ecosystems, determining where other species are able to life, grow and breed. Sea spurge invades open sand areas in coastal environments, blanketing the nesting sites of birds, and displacing other plants and animals. In Australia, Pied oyster catchers and fairy tern colonies have been affected, causing concern for their relatives here in Aotearoa.
Species at risk: Habitats at risk:
Tōrea/oystercatchers Active sand dunes
Tara iti/fairy terns West Coast beaches on both islands
Holloway’s crystalwort
There’s also the matter of the toxic sap:
In 2021, the West Coast Regional Council asked locals to report occurrences of sea spurge, but warned to avoid touching the plant itself. In addition to the accidental spread of seeds, painful rashes can result from contact with the oozing, milky sap. Into the bargain, if it gets in your eyes the subsequent damage can cause temporary blindness.
Fun Fact: All spurges (or Euphorbia) share poisonous, latex-like sap, and some species have even been used to make poison arrowheads! |
What keeps sea spurge in check in its natural range?
If offered a meal of noxious sap most of us would prefer to go hungry! Yet, for the caterpillars of certain species of hawk moth, the oozings of a sea spurge is equivalent to a nice bowl of vichyssoise. The spurge hawk-moth (Hyles euphorbiae) occurs across Europe and the caterpillar’s appetite for spurges has led to it being employed as an agent of biological control in some areas of invasion.
Action stations!
In the past, Australasia and the Pacific haven’t fared well with the introduction of agents of biological control (such as stoats, ferrets, weasels, cane toads), so extensive research is undertaken and takes many years to ensure any biological control is the correct tool for the New Zealand environment.
In Aotearoa other solutions are vital in controlling sea spurge. So, what are we doing?
Looking to our neighbor’s efforts, our vigilance and persistence can help keep sea spurge at bay. In Tasmania, an environmental care group called Wildcare SPRATS (Sea Spurge Remote Area Teams) utilise a three-point model: careful planning, community engagement, and agency partnership – and have had terrific results.
Between founding in 2007 and 2017, teams of volunteers under the SPRATS banner removed 14 million plants from Tasmanian beaches. Now, their model is being used to combat marram grass and blackberry infestations.
In Aotearoa, the Ministry for Primary Industries and Department of Conservation
have started control measures to detect and eradicate sea spurge, and they need your help. Vistors to costal areas can help with finding locations of pest species like sea spurge to help ensure effective pest management
Download Find-a-Pest and report potential sightings
to help keep our beaches free of sea spurge.
Article written by Kerry Donovan-Brown for Find-A-Pest